Semiconductor chip assembly with bumped terminal and filler

ABSTRACT

A semiconductor chip assembly includes a semiconductor chip that includes a conductive pad, a conductive trace that includes a routing line, a bumped terminal and a filler, a connection joint that electrically connects the routing line and the pad, and an encapsulant. The routing line contacts the bumped terminal and the filler and extends laterally beyond the bumped terminal and the filler, and the filler contacts the bumped terminal in a cavity that extends through the bumped terminal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.11/586,295 filed Oct. 25, 2006, now abandoned which is a continuation ofU.S. application Ser. No. 10/994,836 filed Nov. 22, 2004, now U.S. Pat.No. 7,132,741 each of which is incorporated by reference.

U.S. application Ser. No. 10/994,836 filed Nov. 22, 2004 also claims thebenefit of U.S. Provisional Application Ser. No. 60/523,566 filed Nov.20, 2003, which is incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor chip assembly, and moreparticularly to a semiconductor chip assembly with a conductive tracethat includes a routing line and a filler and its method of manufacture.

2. Description of the Related Art

Semiconductor chips have input/output pads that must be connected toexternal circuitry in order to function as part of an electronic system.The connection media is typically an array of metallic leads (e.g., alead frame) or a support circuit (e.g., a substrate), although theconnection can be made directly to a circuit panel (e.g., a motherboard). Several connection techniques are widely used. These includewire bonding, tape automated bonding (TAB) and flip-chip bonding.

Wire bonding is by far the most common and economical connectiontechnique. In this approach, wires are bonded, one at a time, from thechip to external circuitry by thermocompression, thermosonic orultrasonic processes. In thermocompression bonding, fine gold wire isfed from a spool through a clamp and a capillary. A thermal source isswept past an end of the wire to form a wire ball that protrudes fromthe capillary. The chip or capillary is then heated to about 200 to 300°C., the capillary is brought down over an aluminum pad, the capillaryexerts pressure on the wire ball, and the wire ball forms a ball bond onthe pad. The capillary is then raised and moved to a terminal on thesupport circuit, the capillary is brought down again, and thecombination of force and temperature forms a wedge bond between the wireand the terminal. Thus, the connection between the pad and the terminalincludes the ball bond (which only contacts the pad), the wedge bond(which only contacts the terminal) and the wire between the bonds. Afterraising the capillary again, the wire is ripped from the wedge bond, thethermal source is swept past the wire to form a new wire ball, and theprocess is repeated for other pads on the chip. Thermosonic bonding issimilar to thermocompression bonding but adds ultrasonic vibration asthe ball and wedge bonds are formed so that less heat is necessary.Ultrasonic bonding uses aluminum wire to form wedge bonds withoutapplying heat. There are many variations on these basic methods.

TAB involves bonding gold-bumped pads on the chip to external circuitryon a polymer tape using thermocompression bonding. TAB requiresmechanical force such as pressure or a burst of ultrasonic vibration andelevated temperature to accomplish metallurgical welding between thewires or bumps and the designated surface.

Flip-chip bonding involves providing pre-formed solder bumps on thepads, flipping the chip so that the pads face down and are aligned withand contact matching bond sites, and melting the solder bumps to wet thepads and the bond sites. After the solder reflows it is cooled down andsolidified to form solder joints between the pads and the bond sites.Organic conductive adhesive bumps with conductive fillers in polymerbinders have been used in place of solder bumps, but they do notnormally form a metallurgical interface in the classical sense. A majoradvantage of flip-chip bonding over wiring bonding and TAB is that itprovides shorter connection paths between the chip and the externalcircuitry, and therefore has better electrical characteristics such asless inductive noise, cross-talk, propagation delay and waveformdistortion. In addition, flip-chip bonding requires minimal mountingarea and weight which results in overall cost saving since no extrapackaging and less circuit board space are used.

While flip-chip technology has tremendous advantages over wire bondingand TAB, its cost and technical limitations are significant. Forinstance, the cost of forming bumps on the pads is significant. Inaddition, an adhesive is normally underfilled between the chip and thesupport circuit to reduce stress on the solder joints due to thermalmismatch between the chip and the support circuit, and the underfillingprocess increases both manufacturing complexity and cost.

Other techniques besides wire bonding, TAB and flip-chip technologieshave been developed to provide connection joints that electricallyconnect pads on chips to external conductive traces. These connectionjoints can be formed by electroplated metal, electrolessly plated metal,solder or conductive adhesive.

Electroplating provides deposition of an adherent metallic coating ontoa conductive object placed into an electrolytic bath composed of asolution of the salt of the metal to be plated. Using the terminal as ananode (possibly of the same metal as the one used for plating), a DCcurrent is passed through the solution affecting transfer of metal ionsonto the cathode surface. As a result, the metal continuallyelectroplates on the cathode surface. Electroplating using AC currenthas also been developed. Electroplating is relatively fast and easy tocontrol. However, a plating bus is needed to supply current whereelectroplating is desired. The plating bus creates design constraintsand must be removed after the electroplating occurs. Non-uniform platingmay arise at the bottom of relatively deep through-holes due to poorcurrent density distribution. Furthermore, the electrolytic bath isrelatively expensive.

Electroless plating provides metal deposition by an exchange reactionbetween metal complexes in a solution and a catalytic metal thatactivates or initiates the reaction. As a result, the electroless metalcontinually plates (i.e., deposits or grows) on the catalytic metal.Advantageously, the reaction does not require externally appliedelectric current. Therefore, electroless plating can proceed without aplating bus. However, electroless plating is relatively slow.Furthermore, the electroless bath is relatively expensive.

Solder joints are relatively inexpensive, but exhibit increasedelectrical resistance as well as cracks and voids over time due tofatigue from thermo-mechanical stresses. Further, the solder istypically a tin-lead alloy and lead-based materials are becoming farless popular due to environmental concerns over disposing of toxicmaterials and leaching of toxic materials into ground water supplies.

Conductive adhesive joints with conductive fillers in polymer bindersare relatively inexpensive, but do not normally form a metallurgicalinterface in the classical sense. Moisture penetration through thepolymer binder may induce corrosion or oxidation of the conductivefiller particles resulting in an unstable electrical connection.Furthermore, the polymer binder and the conductive filler may degradeleading to an unstable electrical connection. Thus, the conductiveadhesive may have adequate mechanical strength but poor electricalcharacteristics.

Accordingly, each of these connection joint techniques has variousadvantages and disadvantages. The optimal approach for a givenapplication depends on design, reliability and cost considerations.

The semiconductor chip assembly is subsequently connected to anothercircuit such as a printed circuit board (PCB) or mother board duringnext level assembly. Different semiconductor assemblies are connected tothe next level assembly in different ways. For instance, ball grid array(BGA) packages contain an array of solder balls, and land grid array(LGA) packages contain an array of metal pads that receive correspondingsolder traces on the PCB.

Thermo-mechanical wear or creep of the solder joints that connect thesemiconductor chip assembly to the next level assembly is a major causeof failure in most board assemblies. This is because non-uniform thermalexpansion and/or contraction of different materials causes mechanicalstress on the solder joints.

Thermal mismatch induced solder joint stress can be reduced by usingmaterials having a similar coefficient of thermal expansion (CTE).However, due to large transient temperature differences between the chipand other materials during power-up of the system, the induced solderjoint stress makes the assembly unreliable even when the chip and theother materials have closely matched thermal expansion coefficients.

Thermal mismatch induced solder joint stress can also be reduced byproper design of the support circuit. For instance, BGA and LGA packageshave been designed with pillar post type contact terminals that extendabove the package and act as a stand-off or spacer between the packageand the PCB in order to absorb thermal stress and reduce solder jointfatigue. The higher the aspect ratio of the pillar, the more easily thepillar can flex to follow expansion of the two ends and reduce shearstress.

Conventional approaches to forming the pillar on a wafer or a separatesupport circuit include a bonded interconnect process (BIP) and platingusing photoresist.

BIP forms a gold ball on a pad of the chip and a gold pin extendingupwardly from the gold ball using a thermocompression wire bonder.Thereafter, the gold pin is brought in contact with a molten solder bumpon a support circuit, and the solder is reflowed and cooled to form asolder joint around the gold pin. A drawback to this approach is thatwhen the wire bonder forms the gold ball on the pad it appliessubstantial pressure to the pad which might destroy active circuitrybeneath the pad. In addition, gold from the pin can dissolve into thesolder to form a gold-tin intermetallic compound which mechanicallyweakens the pin and therefore reduces reliability.

U.S. Pat. No. 5,722,162 discloses fabricating a pillar by electroplatingthe pillar on a selected portion of an underlying metal exposed by anopening in photoresist and then stripping the photoresist. Although itis convenient to use photoresist to define the location of the pillar,electroplating the pillar in an opening in the photoresist has certaindrawbacks. First, the photoresist is selectively exposed to light thatinitiates a reaction in regions of the photoresist that correspond tothe desired pattern. Since photoresist is not fully transparent andtends to absorb the light, the thicker the photoresist, the poorer thepenetration efficiency of the light. As a result, the lower portion ofthe photoresist might not receive adequate light to initiate or completethe intended photo-reaction. Consequently, the bottom portion of theopening in the photoresist might be too narrow, causing a pillar formedin the narrowed opening to have a diameter that decreases withdecreasing height. Such a pillar has a high risk of fracturing at itslower portion in response to thermally induced stress. Furthermore,photoresist residue on the underlying metal might cause the pillar tohave poor quality or even prevent the pillar from being formed. Second,if the photoresist is relatively thick (such as 100 microns or more),the photoresist may need to be applied with multiple coatings andreceive multiple light exposures and bakes, which increases cost andreduces yield. Third, if the photoresist is relatively thick, theelectroplated pillar may be non-uniform due to poor current densitydistribution in the relatively deep opening. As a result, the pillar mayhave a jagged or pointed top surface instead of a flat top surface thatis better suited for providing a contact terminal for the next levelassembly.

In view of the various development stages and limitations in currentlyavailable semiconductor chip assemblies, there is a need for asemiconductor chip assembly that is cost-effective, reliable,manufacturable, versatile, provides a vertical conductor with excellentmechanical and electrical properties, and makes advantageous use theparticular connection joint technique best suited for a givenapplication.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a semiconductor chipassembly with a chip and a conductive trace that provides a low cost,high performance, high reliability package.

Another object of the present invention is to provide a convenient,cost-effective method for manufacturing a semiconductor chip assembly.

The present invention provides a semiconductor chip assembly thatincludes a semiconductor chip that includes a conductive pad, aconductive trace that includes a routing line, a bumped terminal and afiller, a connection joint that electrically connects the routing lineand the pad, and an encapsulant. The routing line is adjacent to thebumped terminal and extends laterally beyond the bumped terminal and thefiller, and the filler contacts the bumped terminal in a cavity thatextends through the bumped terminal.

The present invention also provides a semiconductor chip assembly thatincludes a semiconductor chip that includes a conductive pad, aconductive trace that includes a routing line, a bumped terminal and afiller, a connection joint that electrically connects the routing lineand the pad, and an encapsulant. The routing line is integral with thebumped terminal and extends laterally beyond the bumped terminal and thefiller, and the filler contacts the bumped terminal in a cavity thatextends through the bumped terminal.

The present invention also provides a semiconductor chip assembly thatincludes a semiconductor chip that includes a conductive pad, aconductive trace that includes a routing line, a bumped terminal and afiller, a connection joint that electrically connects the routing lineand the pad, and an encapsulant. The routing line contacts the bumpedterminal and the filler and extends laterally beyond the bumped terminaland the filler, and the filler contacts the bumped terminal in a cavitythat extends through the bumped terminal.

The present invention also provides a semiconductor chip assembly thatincludes a semiconductor chip that includes a conductive pad, aconductive trace that includes a routing line and a filler, a connectionjoint that electrically connects the routing line and the pad, anencapsulant and an insulative base. The routing line contacts the fillerand extends laterally beyond the filler, and the filler contacts theinsulative base in an aperture that extends through the insulative base.

In accordance with an aspect of the invention, a semiconductor chipassembly includes a semiconductor chip that includes first and secondopposing surfaces, wherein the first surface of the chip includes aconductive pad, a conductive trace that includes a routing line, abumped terminal and a filler, wherein the bumped terminal includes acavity, a connection joint that electrically connects the routing lineand the pad, and an encapsulant that includes first and second opposingsurfaces. The first surface of encapsulant faces in a first direction,the second surface of the encapsulant faces in a second directionopposite the first direction, the chip is embedded in the encapsulant,the routing line is adjacent to the bumped terminal, extends laterallybeyond the bumped terminal and the filler and extends vertically beyondthe chip in the second direction, the bumped terminal extends verticallybeyond the routing line in the second direction, the cavity extendsthrough the bumped terminal in the first and second directions, thefiller contacts the bumped terminal in the cavity and extends verticallybeyond the routing line in the second direction, and the bumpedterminal, the cavity and the filler are laterally aligned with oneanother at a lateral surface that faces in the second direction and arenot covered in the second direction by the encapsulant or any otherinsulative material of the assembly.

The chip can be the only chip embedded in the encapsulant, oralternatively, multiple chips can be embedded in the encapsulant. Thefirst surface of the chip can face in the first direction and the secondsurface of the chip can face in the second direction, or alternatively,the first surface of the chip can face in the second direction and thesecond surface of the chip can face in the first direction. The chip canextend vertically beyond the routing line, the bumped terminal and thefiller in the first direction. The chip can also extend verticallybeyond the conductive trace in the first direction. In addition, anychip embedded in the encapsulant can extend vertically beyond theconductive trace in the first direction.

The routing line can be integral with the bumped terminal. For instance,the routing line and the bumped terminal can include first and secondmetal layers, wherein the first metal layer is adjacent to the cavityand contacts the filler and extends vertically beyond the second metallayer in the first direction, the second metal layer is spaced from thecavity and is laterally aligned with the first metal layer, the cavityand the filler at the lateral surface, and the first and second metallayers are different metals. The first and second metal layers cancontact one another, the first metal layer can be thicker than thesecond metal layer, and the first metal layer and the filler can havethe same or different composition. For example, the first metal layercan be copper, the second metal layer can be nickel, and the filler canbe copper or solder. Moreover, the routing line and the bumped terminalcan have the same composition and thickness.

The routing line can contact the bumped terminal. For instance, therouting line can contact the bumped terminal, contact the filler withinthe periphery of the cavity and extend vertically beyond the bumpedterminal and the filler in the first direction where the routing linecontacts the bumped terminal and the filler. The routing line can coverthe bumped terminal, the cavity and the filler, or alternatively,overlap but not cover the bumped terminal, the cavity and the filler.Furthermore, the routing line can extend within the cavity and contactthe filler within the cavity, or alternatively, be disposed outside thecavity and contact the filler outside the cavity. For example, therouting line can include a distal end that contacts the filler withinthe cavity and is spaced from the bumped terminal, or alternatively, therouting line can include a distal end that contacts the filler withinthe periphery of the cavity outside the cavity and is spaced from thebumped terminal. As another example, the routing line can include a bentcorner that slants vertically in the second direction as the bent cornerextends laterally into the cavity and the routing line can contact thefiller within the cavity, or alternatively, the routing line can includea bent corner that slants vertically in the first direction as the bentcorner extends laterally into the periphery of the cavity outside of thecavity and the routing line can contact the filler outside the cavity.

The routing line can be disposed vertically beyond the chip in thesecond direction. The routing line can extend within and outside theperiphery of the chip, or alternatively, be disposed outside theperiphery of the chip. The routing line can extend within and outsidethe peripheries of the bumped terminal, the cavity and the filler, oralternatively, be disposed outside the peripheries of the bumpedterminal, the cavity and the filler. The routing line can extendvertically beyond the bumped terminal and the filler in the firstdirection, and can extend laterally beyond the bumped terminal and thefiller towards the chip. The routing line can be essentially flat andparallel to the first and second surfaces of the chip, and can extendvertically less than the bumped terminal extends vertically and lessthan the filler extends vertically.

The routing line can be in an electrically conductive path between thebumped terminal and any chip embedded in the encapsulant and between thefiller and any chip embedded in the encapsulant. That is, any chipembedded in the encapsulant can be electrically connected to the bumpedterminal and the filler by an electrically conductive path that includesthe routing line.

The bumped terminal can not extend beyond the routing line in the firstdirection. The bumped terminal can be disposed vertically beyond therouting line in the second direction. The bumped terminal can bedisposed within or outside the periphery of the chip. The bumpedterminal can have a curved shape in the first and second directions anda uniform thickness. The bumped terminal can surround the filler andonly the filler at the lateral surface, be adjacent to the filler at thelateral surface and have a smaller surface area than the filler at thelateral surface. Furthermore, the bumped terminal can form a ring at thelateral surface.

The cavity can extend across a majority of a height and diameter of thebumped terminal and a majority of a height and diameter of the filler.The cavity can extend vertically beyond the routing line in the seconddirection and can have a diameter that decreases as the cavity extendsin the second direction.

The cavity can include first and second opposing ends that are adjacentto the bumped terminal and curved tapered sidewalls therebetween,wherein the first end of the cavity faces in the first direction, thesecond end of the cavity faces in the second direction, and the curvedtapered sidewalls are adjacent to the first and second ends and slantinwardly towards the second end. Furthermore, the second end of thecavity can be disposed within a surface area of the first end of thecavity, and a surface area of the first end of the cavity can be atleast 20 percent larger than a surface area of the second end of thecavity. Similarly, the second end of the cavity can be disposed within asurface area of the bumped terminal, and a surface area of the bumpedterminal can be at least 20 percent larger than a surface area of thesecond end of the cavity. Similarly, the second end of the cavity can bedisposed within a surface area of the filler, and a surface area of thefiller can be at least 20 percent larger than a surface area of thesecond end of the cavity.

The filler can overlap or not overlap the routing line in the firstdirection, cover or not cover the bumped terminal in the firstdirection, cover or not cover the cavity in the first direction, fill ornot fill the cavity, and have a uniform or non-uniform thickness. Thefiller can be disposed within the cavity, or alternatively, extend intoand outside the cavity. The filler can fill a majority or essentiallyall of the cavity, and a majority or essentially all of the filler canbe disposed within the cavity.

The filler can extend vertically beyond the chip in the first direction,or alternatively, not extend vertically beyond the chip in the firstdirection. The filler can extend vertically beyond the routing line, thebumped terminal and the cavity in the first direction, or alternatively,extend vertically beyond the bumped terminal and the cavity but not therouting line in the first direction, or alternatively, not extendvertically beyond the routing line, the bumped terminal or the cavity inthe first direction. The filler can be disposed within or outside theperiphery of the chip. The filler can include first and second opposingsurfaces, wherein the first surface of the filler faces in the firstdirection, and the second surface of the filler faces in the seconddirection. The first surface of the filler can extend into, extend intoand outside, or not extend into the cavity.

The connection joint can extend between and electrically connect therouting line and the pad. The connection joint can be electroplatedmetal, electrolessly plated metal, solder, conductive adhesive, a studbump or a wire bond.

The encapsulant can contact the chip, the routing line, the bumpedterminal and the filler. The encapsulant can cover the chip, the routingline and the bumped terminal in the first direction. The encapsulant cancover the filler in the first direction, or alternatively, theencapsulant can be laterally aligned with the filler at a second lateralsurface that faces in the first direction and the encapsulant cansurround and be adjacent to the filler at the second lateral surface.The encapsulant can extend into or not extend into the cavity. Theencapsulant can contact the routing line and the filler within oroutside the cavity. The encapsulant and the filler can fill the cavity,or alternatively, the encapsulant, the routing line and the filler canfill the cavity.

The lateral surface can be an exposed major surface of the assembly.

The assembly can include an insulative base that contacts the routingline and the bumped terminal, is overlapped by the chip and extendsvertically beyond the chip, the routing line and the encapsulant in thesecond direction. The insulative base can contact the encapsulant and bespaced from the chip and the filler. The insulative base can belaterally aligned with the bumped terminal, the cavity and the filler atthe lateral surface and can surround and be adjacent to the bumpedterminal at the lateral surface.

The assembly can include an insulative adhesive that contacts the chipand the encapsulant and extends vertically beyond the chip in the seconddirection. The insulative adhesive can cover the bumped terminal and thefiller in the first direction. The insulative adhesive can extend intoor not extend into the cavity. The insulative adhesive can contact therouting line and the filler within or outside the cavity. The insulativeadhesive and the filler can fill the cavity, or alternatively, theinsulative adhesive, the routing line and the filler can fill thecavity.

The assembly can include a contact terminal that contacts and iselectrically connected to the bumped terminal and the filler, is spacedfrom the routing line and the connection joint and extends verticallybeyond the chip, the routing line, the bumped terminal, the filler, theconnection joint, the encapsulant and the insulative base in the seconddirection. The contact terminal can be exposed and the routing line, thebumped terminal and the filler can be unexposed. The contact terminalcan be electrolessly plated metal, solder, or both.

The assembly can omit the bumped terminal, and instead the filler cancontact the insulative base in an aperture that extends through theinsulative base in the first and second directions. In this instance,the insulative base can be laterally aligned with the filler and theaperture at the lateral surface and can surround and be adjacent to thefiller at the lateral surface, and the aperture can have the same size,shape and location as the cavity.

The assembly can be a first-level package that is a single-chip ormulti-chip package. Furthermore, the assembly can be devoid of a printedcircuit board.

The present invention provides a method of making a semiconductor chipassembly that includes providing a metal base, a routing line, a bumpedterminal and a filler, then mechanically attaching a semiconductor chipto the metal base, the routing line, the bumped terminal and the filler,then forming an encapsulant, then etching the metal base to expose thebumped terminal, and then exposing the filler.

The present invention also provides a method of making a semiconductorchip assembly that includes providing a metal base, a routing line, abumped terminal and a filler, wherein the routing line is adjacent tothe bumped terminal, then mechanically attaching a semiconductor chip tothe metal base, the routing line, the bumped terminal and the filler,then forming an encapsulant, then etching the metal base to expose thebumped terminal, and then grinding the bumped terminal to expose thefiller.

The present invention also provides a method of making a semiconductorchip assembly that includes providing a metal base, a routing line, abumped terminal and a filler, wherein the routing line is integral withthe bumped terminal, then mechanically attaching a semiconductor chip tothe metal base, the routing line, the bumped terminal and the filler,then forming an encapsulant, then etching the metal base to expose thebumped terminal, and then grinding the bumped terminal to expose thefiller.

The present invention also provides a method of making a semiconductorchip assembly that includes providing a metal base, a routing line, abumped terminal and a filler, wherein the routing line contacts thebumped terminal and the filler, then mechanically attaching asemiconductor chip to the metal base, the routing line, the bumpedterminal and the filler, then forming an encapsulant, then etching themetal base to expose the bumped terminal, and then grinding the bumpedterminal to expose the filler.

The present invention also provides a method of making a semiconductorchip assembly includes providing a metal base, a routing line, a bumpedterminal and a filler, wherein the routing line contacts the bumpedterminal and the filler, then mechanically attaching a semiconductorchip to the metal base, the routing line, the bumped terminal and thefiller, then forming an encapsulant, then etching the metal base toexpose the bumped terminal, then etching the bumped terminal to exposethe filler, then forming an insulative base, and then grinding theinsulative base to expose the filler.

In accordance with another aspect of the invention, a method of making asemiconductor chip assembly includes providing a metal base, a routingline, a bumped terminal and a filler, wherein the routing line isadjacent to the bumped terminal and contacts the metal base, the bumpedterminal contacts the metal base in a recess in the metal base andincludes a cavity that extends into and faces away from the recess, andthe filler contacts the bumped terminal in the cavity and extends intothe recess, then mechanically attaching a semiconductor chip to themetal base, the routing line, the bumped terminal and the filler,wherein the chip includes first and second opposing surfaces, and thefirst surface of the chip includes a conductive pad, forming aconnection joint that electrically connects the routing line and thepad, forming an encapsulant after attaching the chip to the metal base,the routing line, the bumped terminal and the filler, wherein theencapsulant includes a first surface that faces in a first direction anda second surface that faces in a second direction opposite the firstdirection, the encapsulant covers the chip and extends vertically beyondthe chip, the metal base, the routing line, the bumped terminal and thefiller in the first direction, the chip is embedded in the encapsulant,the metal base extends vertically beyond the chip, the routing line, thebumped terminal and the filler in the second direction, the routing lineextends laterally beyond the bumped terminal and the filler, the bumpedterminal extends vertically beyond the routing line and the filler inthe second direction, the filler extends vertically beyond the routingline in the second direction, and the cavity extends through the bumpedterminal in the first direction but not the second direction and iscovered by the metal base and the bumped terminal in the seconddirection, etching the metal base after forming the encapsulant, therebyexposing the routing line and the bumped terminal without exposing thefiller, and then grinding the bumped terminal, thereby exposing thefiller in the cavity such that the cavity extends through the bumpedterminal in the second direction.

The method can include forming the routing line, the bumped terminal andthe filler by depositing the routing line and the bumped terminal on themetal base, and then depositing the filler on the bumped terminal.

The method can include providing the metal base, then forming the recessin the metal base, then forming the routing line and the bumped terminalon the metal base, wherein the routing line and the bumped terminal areintegral with one another and contact the metal base, the routing lineis disposed outside the recess, and the bumped terminal extends into therecess and includes the cavity that extends into and faces away from therecess, and then forming the filler on the bumped terminal, wherein thefiller contacts the bumped terminal in the cavity, is spaced from themetal base and extends into the recess.

The method can include forming the routing line and the bumped terminalby forming an etch mask on the metal base that includes an opening thatexposes the metal base, etching the metal base through the opening inthe etch mask, thereby forming the recess in the metal base, removingthe etch mask, then forming a plating mask on the metal base thatincludes an opening that exposes the metal base, electroplating therouting line and the bumped terminal on the metal base through theopening in the plating mask, and then depositing the filler on thebumped terminal. In this manner, the routing line and the bumpedterminal can be simultaneously electroplated on the metal base, and thenthe filler can be deposited on the bumped terminal.

The method can include forming the routing line, the bumped terminal andthe filler by depositing the bumped terminal on the metal base, thendepositing the filler on the bumped terminal, and then depositing therouting line on the metal base, the bumped terminal and the filler.

The method can include providing the metal base, then forming the recessin the metal base, then forming the bumped terminal on the metal base,wherein the bumped terminal extends into the recess and includes thecavity that extends into and faces away from the recess, then formingthe filler on the bumped terminal, wherein the filler contacts thebumped terminal in the cavity, is spaced from the metal base and extendsinto the recess, and then forming the routing line on the metal base,the bumped terminal and the filler.

The method can include forming the routing line and the bumped terminalby forming a first plating mask on the metal base that includes anopening that exposes the metal base, etching the metal base through theopening in the first plating mask using the first plating mask as anetch mask, thereby forming the recess in the metal base, thenelectroplating the bumped terminal on the metal base through the openingin the first plating mask, then depositing the filler on the bumpedterminal and removing the first plating mask, then forming a secondplating mask on the metal base that includes an opening that exposes themetal base, the bumped terminal and the filler, and electroplating therouting line on the metal base, the bumped terminal and the fillerthrough the opening in the second plating mask. In this manner, thebumped terminal can be electroplated on the metal base, then the fillercan be deposited on the bumped terminal, and then the routing line canbe electroplated on the metal base, the bumped terminal and the filler.

The method can include forming the filler by electroplating the filleron the bumped terminal. For example, the method can include forming aplating mask on the metal base that includes an opening that exposes thebumped terminal, electroplating the filler on the bumped terminalthrough the opening in the plating mask, and then removing the platingmask. As another example, the method can include electroplating thefiller on the bumped terminal through the opening in the plating maskthrough which the bumped terminal was electroplated, and then removingthe plating mask. Alternatively, the method can include forming thefiller by depositing solder paste on the bumped terminal and thenhardening the solder paste. Alternatively, the method can includeforming the filler by depositing conductive adhesive on the bumpedterminal and then hardening the conductive adhesive. In this manner, thefiller can be electroplated metal, solder or conductive adhesive.

The method can include attaching the chip to the metal base, the routingline, the bumped terminal and the filler by disposing an insulativeadhesive between the chip and the metal base and then hardening theinsulative adhesive.

The method can include forming the encapsulant by transfer molding orcuring.

The method can include grinding the encapsulant without grinding thebumped terminal and without grinding the filler, and then grinding theencapsulant and the filler without grinding the bumped terminal, therebyexposing the filler outside the cavity. Grinding the encapsulant and thefiller can laterally align the encapsulant and the filler at the secondlateral surface.

The method can include forming the connection joint by plating theconnection joint between the routing line and the pad. For instance, theconnection joint can be electroplated or electrolessly plated betweenthe routing line and the pad. Alternatively, the method can includeforming the connection joint by depositing a non-solidified materialbetween the routing line and the pad and then hardening thenon-solidified material. For instance, solder paste can be depositedbetween the routing line and the pad and then hardened by reflowing, orconductive adhesive can be deposited between the routing line and thepad and then hardened by curing. Alternatively, the method can includeforming the connection joint by wire bonding. For instance, the wirebond can extend vertically beyond the chip and the routing line in thefirst direction when the first surface of the chip faces in the firstdirection, or alternatively, the wire bond can extend vertically beyondthe chip and the routing line in the second direction when the firstsurface of the chip faces in the second direction.

The method can include etching the metal base, thereby eliminatingcontact area between the metal base and the routing line and between themetal base and the bumped terminal. Etching the metal base can removeall of the metal base within the periphery of the pad, can remove all ofthe metal base within the periphery of the chip, and can remove themetal base.

The method can include etching the metal base, thereby electricallyisolating the routing line from other routing lines formed on the metalbase and electrically isolating the pad from other pads of the chip. Forinstance, the method can include forming the connection joint by wirebonding, then forming the encapsulant, and then etching the metal base,thereby electrically isolating the routing line from the other routinglines and the pad from other pads. Alternatively, the method can includeforming the encapsulant, then forming the connection joint byelectroplating using the metal base as a plating bus, and then etchingthe metal base, thereby electrically isolating the routing line from theother routing lines and the pad from the other pads.

The method can include forming the insulative base by depositing theinsulative base such that the insulative base covers and extendsvertically beyond the chip, the routing line, the bumped terminal andthe filler in the second direction and the bumped terminal and thefiller are not exposed and then grinding the insulative base such thatthe bumped terminal is exposed, or alternatively, depositing theinsulative base such that the insulative base does not cover the bumpedterminal in the second direction and the bumped terminal is exposed.

The method can include grinding the insulative base without grinding thebumped terminal and without grinding the filler, then grinding theinsulative base and the bumped terminal without grinding the filler, andthen grinding the insulative base, the bumped terminal and the filler.Grinding the insulative base and the bumped terminal can laterally alignthe insulative base and the bumped terminal at the lateral surface.Likewise, grinding the insulative base, the bumped terminal and thefiller can laterally align the insulative base, the bumped terminal, thecavity and the filler at the lateral surface.

The method can include plasma etching the insulative base after grindingthe insulative base, the bumped terminal and the filler such that theinsulative base is recessed relative to the bumped terminal and thefiller in the second direction, and thus the bumped terminal and thefiller extend vertically beyond the insulative base in the seconddirection.

The method can include forming the contact terminal on the bumpedterminal and the filler after grinding the insulative base, the bumpedterminal and the filler by electrolessly plating metal on the bumpedterminal and the filler, or alternatively, by depositing solder paste onthe bumped terminal and the filler and then hardening the solder paste,or alternatively, by electrolessly plating metal on the bumped terminaland the filler, then depositing solder paste on the electrolessly platedmetal and then hardening the solder paste.

The method can include etching the bumped terminal after etching themetal base, thereby exposing the filler, then forming the insulativebase such that the filler contacts the insulative base in the apertureand the aperture extends through the insulative base in the firstdirection but not the second direction and is covered by the insulativebase in the second direction, then grinding the insulative base withoutgrinding the filler, and then grinding the insulative base and thefiller, thereby exposing the filler in the aperture such that theaperture extends through the insulative base in the second direction andthe filler, the insulative base and the aperture are laterally alignedwith one another at the lateral surface.

The method can include attaching the chip to the metal base, the routingline, the bumped terminal and the filler and then forming the connectionjoint, or alternatively, simultaneously attaching the chip to the metalbase, the routing line, the bumped terminal and the filler and formingthe connection joint.

The method can include forming the connection joint and then forming theencapsulant, or alternatively, forming the encapsulant and then formingthe connection joint.

The method can include forming the connection joint and then etching themetal base, or alternatively, etching the metal base and then formingthe connection joint.

The method can include forming the encapsulant, then forming theconnection joint and then etching the metal base, or alternatively,forming the encapsulant, then etching the metal base and then formingthe connection joint.

The method can include grinding the encapsulant and the filler and thenforming the insulative base, or alternatively, forming the insulativebase and then grinding the encapsulant and the filler.

The method can include grinding the encapsulant and the filler and thengrinding the insulative base, the bumped terminal and the filler, oralternatively, grinding the insulative base, the bumped terminal and thefiller and then grinding the encapsulant and the filler.

An advantage of the present invention is that the semiconductor chipassembly can be manufactured conveniently and cost effectively. Anotheradvantage is that the encapsulant can be provided before the metal baseis etched and removed, thereby enhancing the mechanical support andprotection for the routing line, the bumped terminal and the filler.Another advantage is that the filler can contact the bumped terminal inthe cavity, thereby enhancing reliability if the bumped terminal isdamaged. Another advantage is that the connection joint can be made froma wide variety of materials and processes, thereby making advantageoususe of mature connection joint technologies in a unique and improvedmanufacturing approach. Another advantage is that the assembly need notinclude wire bonds or TAB leads, although the process is flexible enoughto accommodate these techniques if desired. Another advantage is thatthe assembly can be manufactured using low temperature processes whichreduces stress and improves reliability. A further advantage is that theassembly can be manufactured using well-controlled processes which canbe easily implemented by circuit board, lead frame and tapemanufacturers. Still another advantage is that the assembly can bemanufactured using materials that are compatible with copper chip andlead-free environmental requirements.

These and other objects, features and advantages of the invention willbe further described and more readily apparent from a review of thedetailed description of the preferred embodiments which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description of the preferred embodiments can bestbe understood when read in conjunction with the following drawings, inwhich:

FIGS. 1A-23A are cross-sectional views showing a method of making asemiconductor chip assembly in accordance with a first embodiment of thepresent invention;

FIGS. 1B-23B are top plan views corresponding to FIGS. 1A-23A,respectively;

FIGS. 1C-23C are bottom plan views corresponding to FIGS. 1A-23A,respectively;

FIGS. 24A, 24B and 24C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with asecond embodiment of the present invention;

FIGS. 25A, 25B and 25C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with athird embodiment of the present invention;

FIGS. 26A, 26B and 26C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with afourth embodiment of the present invention;

FIGS. 27A, 27B and 27C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with afifth embodiment of the present invention;

FIGS. 28A, 28B and 28C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with asixth embodiment of the present invention;

FIGS. 29A, 29B and 29C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with aseventh embodiment of the present invention;

FIGS. 30A, 30B and 30C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with aneighth embodiment of the present invention;

FIGS. 31A, 31B and 31C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with aninth embodiment of the present invention;

FIGS. 32A, 32B and 32C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with atenth embodiment of the present invention;

FIGS. 33A-54A are cross-sectional views showing a method of making asemiconductor chip assembly in accordance with an eleventh embodiment ofthe present invention;

FIGS. 33B-54B are top plan views corresponding to FIGS. 33A-54A,respectively;

FIGS. 33C-54C are bottom plan views corresponding to FIGS. 33A-54A,respectively;

FIGS. 55A, 55B and 55C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with atwelfth embodiment of the present invention;

FIGS. 56A, 56B and 56C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with athirteenth embodiment of the present invention;

FIGS. 57A, 57B and 57C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with afourteenth embodiment of the present invention;

FIGS. 58A, 58B and 58C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with afifteenth embodiment of the present invention;

FIGS. 59A, 59B and 59C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with asixteenth embodiment of the present invention;

FIGS. 60A, 60B and 60C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with aseventeenth embodiment of the present invention;

FIGS. 61A, 61B and 61C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with aneighteenth embodiment of the present invention;

FIGS. 62A, 62B and 62C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with anineteenth embodiment of the present invention; and

FIGS. 63A, 63B and 63C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with atwentieth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1A-23A, 1B-23B and 1C-23C are cross-sectional, top and bottomviews, respectively, of a method of making a semiconductor chip assemblyin accordance with a first embodiment of the present invention. In thefirst embodiment, the routing line is integral with the bumped terminal.

FIGS. 1A, 1B and 1C are cross-sectional, top and bottom views,respectively, of semiconductor chip 110 which is an integrated circuitin which various transistors, circuits, interconnect lines and the likeare formed (not shown). Chip 110 includes opposing major surfaces 112and 114 and has a thickness (between surfaces 112 and 114) of 150microns. Surface 112 is the active surface and includes conductive pad116 and passivation layer 118.

Pad 116 is substantially aligned with passivation layer 118 so thatsurface 112 is essentially flat. Alternatively, if desired, pad 116 canextend above or be recessed below passivation layer 118. Pad 116provides a bonding site to electrically couple chip 110 with externalcircuitry. Thus, pad 116 can be an input/output pad or a power/groundpad. Pad 116 has a length and width of 100 microns.

Pad 116 has an aluminum base that is cleaned by dipping chip 110 in asolution containing 0.05 M phosphoric acid at room temperature for 1minute and then rinsed in distilled water. Pad 116 can have the aluminumbase serve as a surface layer, or alternatively, pad 116 can be treatedto include a surface layer that covers the aluminum base, depending onthe nature of a connection joint that shall subsequently contact thesurface layer. In this embodiment, the connection joint is a gold wirebond. Therefore, pad 116 need not be treated to accommodate thisconnection joint. Alternatively, pad 116 can be treated by depositingseveral metal layers, such as chromium/copper/gold ortitanium/nickel/gold on the aluminum base. The chromium or titaniumlayer provides a barrier for the aluminum base and an adhesive betweenthe overlaying metal and the aluminum base. The metal layers, however,are typically selectively deposited by evaporation, electroplating orsputtering using a mask which is a relatively complicated process.Alternatively, pad 116 is treated by forming a nickel surface layer onthe aluminum base. For instance, chip 110 is dipped in a zinc solutionto deposit a zinc layer on the aluminum base. This step is commonlyknown as zincation. Preferably, the zinc solution contains about 150grams/liter of NaOH, 25 grams/liter of ZnO, and 1 gram/liter of NaNO₃,as well as tartaric acid to reduce the rate at which the aluminum basedissolves. Thereafter, the nickel surface layer is electrolesslydeposited on the zincated aluminum base. A suitable electroless nickelplating solution is Enthone Enplate NI-424 at 85° C.

Chip 110 includes many other pads on surface 112, and only pad 116 isshown for convenience of illustration. In addition, chip 110 has alreadybeen singulated from other chips that it was previously attached to on awafer.

FIGS. 2A, 2B and 2C are cross-sectional, top and bottom views,respectively, of metal base 120 which includes opposing major surfaces122 and 124. Metal base 120 is a copper plate with a thickness of 200microns.

FIGS. 3A, 3B and 3C are cross-sectional, top and bottom views,respectively, of photoresist layers 126 and 128 formed on metal base120. Photoresist layers 126 and 128 are deposited using a dry filmlamination process in which hot rolls simultaneously press photoresistlayers 126 and 128 onto surfaces 122 and 124, respectively. A reticle(not shown) is positioned proximate to photoresist layer 126.Thereafter, photoresist layer 126 is patterned by selectively applyinglight through the reticle, applying a developer solution to remove thephotoresist portion rendered soluble by the light, and then hard baking,as is conventional. As a result, photoresist layer 126 contains anopening that selectively exposes surface 122 of metal base 120, andphotoresist layer 128 remains unpatterned. Photoresist layers 126 and128 have a thickness of 25 microns beyond surfaces 122 and 124,respectively.

FIGS. 4A, 4B and 4C are cross-sectional, top and bottom views,respectively, of recess 130 formed in metal base 120.

Recess 130 is formed by applying a front-side wet chemical etch to theexposed portion of surface 122 using photoresist layer 126 as an etchmask. For instance, a top spray nozzle (not shown) can spray the wetchemical etch on metal base 120 while a bottom spray nozzle (not shown)is deactivated, or the structure can be dipped in the wet chemical etchsince photoresist layer 128 provides back-side protection. The wetchemical etch is highly selective of copper and etches 140 microns intometal base 120. The wet chemical etch also laterally undercuts metalbase 120 relative to metal containment wall 132, causing recess 130 totaper inwardly with increasing depth. As a result, recess 130 extendsfrom surface 122 into but not through metal base 120. Recess 130 has adiameter of 300 microns at surface 122, a depth of 140 microns relativeto surface 122 and is spaced from surface 124 by 60 microns.

A suitable wet chemical etch can be provided by a solution containingalkaline ammonia. The optimal etch time for exposing metal base 120 tothe wet chemical etch in order to form recess 130 with the desireddimensions can be established through trial and error.

FIGS. 5A, 5B and 5C are cross-sectional, top and bottom views,respectively, of metal base 120 after photoresist layers 126 and 128 arestripped. Photoresist layers 126 and 128 are removed using a solvent,such as a mild alkaline solution with a pH of 9, that is highlyselective of photoresist with respect to copper. Therefore, noappreciable amount of metal base 120 is removed.

FIGS. 6A, 6B and 6C are cross-sectional, top and bottom views,respectively, of photoresist layers 132 and 134 formed on metal base120. Photoresist layers 132 and 134 are deposited using a dry filmlamination process in which hot rolls simultaneously press photoresistlayers 132 and 134 onto surfaces 122 and 124, respectively. A reticle(not shown) is positioned proximate to photoresist layer 132.Thereafter, photoresist layer 132 is patterned by selectively applyinglight through the reticle, applying a developer solution to remove thephotoresist portion rendered soluble by the light, and then hard baking,as is conventional. As a result, photoresist layer 132 contains anopening that selectively exposes surface 122 of metal base 120 andrecess 130, and photoresist layer 134 remains unpatterned. Photoresistlayers 132 and 134 have a thickness of 25 microns beyond surfaces 122and 124, respectively.

FIGS. 7A, 7B and 7C are cross-sectional, top and bottom views,respectively, of routing line 136 and bumped terminal 138 formed onmetal base 120.

Routing line 136 contacts metal base 120 at surface 122 outside recess130, and bumped terminal 138 contacts metal base 120 at recess 130.Thus, routing line 136 is disposed outside recess 130, and bumpedterminal 138 is disposed within recess 130, contours to recess 130,covers recess 130 in the upward direction but does not fill recess 130.Routing line 136 and bumped terminal 138 are contiguous with andintegral with one another and have the same composition and thickness.

Routing line 136 and bumped terminal 138 are composed of a nickel layerelectroplated on metal base 120 and a copper layer electroplated on thenickel layer. The nickel layer contacts and is sandwiched between metalbase 120 and the copper layer, the copper layer contacts the nickellayer and is spaced from metal base 120. Thus, the nickel layer isburied beneath the copper layer, and the copper layer is exposed.Routing line 136 and bumped terminal 138 have a thickness of 20 microns.In particular, the nickel layer has a thickness of 1 micron, and thecopper layer has a thickness of 19 microns. For convenience ofillustration, the nickel and copper layers are shown as a single layer.

Routing line 136 and bumped terminal 138 are simultaneously formed by anelectroplating operation using photoresist layers 132 and 134 as platingmasks. Thus, routing line 136 and bumped terminal 138 are formedadditively. Initially, a plating bus (not shown) is connected to metalbase 120, current is applied to the plating bus from an external powersource, and metal base 120 is submerged in an electrolytic nickelplating solution such as Technic Techni Nickel “S” at room temperature.As a result, the nickel layer electroplates (deposits or grows) on theexposed portions of metal base 120. The nickel electroplating operationcontinues until the nickel layer has the desired thickness. Thereafter,the structure is removed from the electrolytic nickel plating solutionand submerged in an electrolytic copper plating solution such as Sel-RexCUBATH M™ at room temperature while current is applied to the platingbus to electroplate the copper layer on the nickel layer. The copperelectroplating operation continues until the copper layer has thedesired thickness. Thereafter, the structure is removed from theelectrolytic copper plating solution and rinsed in distilled water toremove contaminants.

Routing line 136 includes elongated routing portion 142 and enlargedannular portion 144. Elongated routing portion 142 and enlarged annularportion 144 are adjacent to and coplanar with one another. Elongatedrouting portion 142 is a flat planar lead with a width (orthogonal toits elongated length) of 100 microns, and enlarged annular portion 144is a ring with an inner diameter of 300 microns, an outer diameter of400 microns and a width of 50 microns ((400−300)/2). Furthermore,elongated routing portion 142 extends laterally from bumped terminal138, and enlarged annular portion 144 is adjacent to and encirclesbumped terminal 138.

Bumped terminal 138 is a curved hollow dome with a downwardly extendingheight of 140 microns and a diameter of 300 microns. Thus, bumpedterminal 138 extends downwardly beyond routing line 136. Furthermore,bumped terminal 138 includes or defines cavity 146 that is spaced frommetal base 120, extends into and faces away from recess 130 and extendsdownwardly beyond routing line 136.

Cavity 146 is adjacent to and extends across a majority of the heightand diameter of bumped terminal 138 and has a concave, crater-likeshape. Furthermore, cavity 146 extends into but not through bumpedterminal 138, is not covered by bumped terminal 138 in the upwarddirection and is covered by bumped terminal 138 in the downwarddirection. In other words, cavity 146 extends through bumped terminal138 in the upward direction but not the downward direction.

FIGS. 8A, 8B and 8C are cross-sectional, top and bottom views,respectively, of metal base 120, routing line 136 and bumped terminal138 after photoresist layers 132 and 134 are stripped. Photoresistlayers 132 and 134 are removed using a solvent, such as a mild alkalinesolution with a pH of 9, that is highly selective of photoresist withrespect to copper and nickel. Therefore, no appreciable amount of metalbase 120, routing line 136 or bumped terminal 138 is removed.

FIGS. 9A, 9B and 9C are cross-sectional, top and bottom views,respectively, of photoresist layers 150 and 152 formed on metal base120. Photoresist layers 150 and 152 are deposited in liquid form usingroller coating onto surfaces 122 and 124, respectively. A reticle (notshown) is positioned proximate to photoresist layer 150. Thereafter,photoresist layer 150 is patterned by selectively applying light throughthe reticle, applying a developer solution to remove the photoresistportion rendered soluble by the light, and then hard baking, as isconventional. As a result, photoresist layer 150 contains an openingthat selectively exposes routing line 136 and bumped terminal 138, andphotoresist layer 152 remains unpatterned. Photoresist layers 150 and152 each have a thickness of 100 microns beyond surfaces 122 and 124,respectively.

FIGS. 10A, 10B and 10C are cross-sectional, top and bottom views,respectively, of filler 154 formed on bumped terminal 138.

Filler 154 contacts and is electrically connected to routing line 136and bumped terminal 138 and is spaced from metal base 120. Filler 154contacts bumped terminal 138 within cavity 146, covers bumped terminal138 and cavity 146 in the upward direction, extends within and outsidebut does not fill cavity 146 and overlaps but does not cover routingline 136 in the upward direction. Filler 154 is composed of a copperlayer electroplated on routing line 136 and bumped terminal 138 and hasa thickness of 60 microns.

Filler 154 is formed by an electroplating operation using photoresistlayers 150 and 152 as plating masks. Thus, filler 154 is formedadditively. Initially, a plating bus (not shown) is connected to metalbase 120, current is applied to the plating bus from an external powersource, and the structure is submerged in an electrolytic copper platingsolution such as Sel-Rex CUBATH M™ at room temperature while current isapplied to the plating bus to electroplate the copper layer on routingline 136 and bumped terminal 138. The copper electroplating operationcontinues until the copper layer has the desired thickness. Thereafter,the structure is removed from the electrolytic copper plating solutionand rinsed in distilled water to remove contaminants.

Filler 154 includes opposing surfaces 156 and 158. Surface 156 facesupwardly, is spaced from and faces away from routing line 136 and bumpedterminal 138 and is exposed, and surface 158 faces downwardly and facestowards and contacts routing line 136 and bumped terminal 138 and isunexposed. Surfaces 156 and 158 are curved and contour to bumpedterminal 138 and extend within and outside cavity 146.

Filler 154 is disposed outside the periphery of chip 110, extendsupwardly beyond metal base 120, routing line 136 and bumped terminal 138and extends downwardly beyond routing line 136. Furthermore, filler 154overlaps but does not cover routing line 136 in the upward direction andcovers bumped terminal 138 and cavity 146 in the upward direction.

FIGS. 11A, 11B and 11C are cross-sectional, top and bottom views,respectively, of metal base 120, routing line 136, bumped terminal 138and filler 154 after photoresist layers 150 and 152 are stripped.Photoresist layers 150 and 152 are removed using a solvent, such as amild alkaline solution with a pH of 9, that is highly selective ofphotoresist with respect to copper and nickel. Therefore, no appreciableamount of metal base 120, routing line 136, bumped terminal 138 orfiller 154 is removed.

FIGS. 12A, 12B and 12C are cross-sectional, top and bottom views,respectively, of photoresist layers 160 and 162 formed on metal base120. Photoresist layers 160 and 162 are deposited in liquid form usingroller coating onto surfaces 122 and 124, respectively. A reticle (notshown) is positioned proximate to photoresist layer 160. Thereafter,photoresist layer 160 is patterned by selectively applying light throughthe reticle, applying a developer solution to remove the photoresistportion rendered soluble by the light, and then hard baking, as isconventional. As a result, photoresist layer 160 contains an openingthat selectively exposes routing line 136, and photoresist layer 162remains unpatterned. Photoresist layers 160 and 162 each have athickness of 75 microns beyond surfaces 122 and 124, respectively.

FIGS. 13A, 13B and 13C are cross-sectional, top and bottom views,respectively, of plated contact 164 formed on routing line 136.

Plated contact 164 contacts and is electrically connected to routingline 136, and is spaced from metal base 120, bumped terminal 138 andfiller 154. Plated contact 164 is composed of a nickel layerelectroplated on routing line 136 and a gold layer electroplated on thenickel layer. The nickel layer contacts and is sandwiched betweenrouting line 136 and the gold layer, and the gold layer contacts thenickel layer and is spaced from routing line 136. Thus, the nickel layeris buried beneath the gold layer, and the gold layer is exposed. Platedcontact 164 has a thickness of 3.5 microns. In particular, the nickellayer has a thickness of 3 microns, and the gold layer has a thicknessof 0.5 microns. For convenience of illustration, the nickel and goldlayers are shown as a single layer.

Plated contact 164 is formed by an electroplating operation usingphotoresist layers 160 and 162 as plating masks. Thus, plated contact164 is formed additively. Initially, a plating bus (not shown) isconnected to metal base 120, current is applied to the plating bus froman external power source, and the structure is submerged in anelectrolytic nickel plating solution such as Technic Techni Nickel “S”at room temperature. As a result, the nickel layer electroplates on theexposed portion of routing line 136. The nickel electroplating operationcontinues until the nickel layer has the desired thickness. Thereafter,the structure is removed from the electrolytic nickel plating solutionand submerged in an electrolytic gold plating solution such as TechnicOrotemp at room temperature while current is applied to the plating busto electroplate the gold layer on the nickel layer. The goldelectroplating operation continues until the gold layer has the desiredthickness. Thereafter, the structure is removed from the electrolyticgold plating solution and rinsed in distilled water to removecontaminants.

FIGS. 14A, 14B and 14C are cross-sectional, top and bottom views,respectively, of metal base 120, routing line 136, bumped terminal 138,filler 154 and plated contact 164 after photoresist layers 160 and 162are stripped. Photoresist layers 160 and 162 are removed using asolvent, such as a mild alkaline solution with a pH of 9, that is highlyselective of photoresist with respect to copper, nickel and gold.Therefore, no appreciable amount of metal base 120, routing line 136,bumped terminal 138, filler 154 or plated contact 164 is removed.

FIGS. 15A, 15B and 15C are cross-sectional, top and bottom views,respectively, of adhesive 166 formed on metal base 120.

Adhesive 166 may include an organic surface protectant such as HK 2000which is promptly applied to the structure after photoresist layer 160is removed to reduce native oxide formation on the exposed coppersurfaces. The use of organic surface protectant layers in insulativeadhesives for semiconductor chip assemblies is well-known in the art.

Thereafter, a liquid resin (A stage) such as polyamic acid is appliedover metal base 120 using stencil printing. During stencil printing, astencil (not shown) is placed over metal base 120, routing line 136,bumped terminal 138, filler 154 and plated contact 164, a stencilopening is aligned with metal base 120 and offset from routing line 136,bumped terminal 138, filler 154 and plated contact 164, and then asqueegee (not shown) pushes the liquid resin along the surface of thestencil opposite metal base 120, routing line 136, bumped terminal 138,filler 154 and plated contact 164, through the stencil opening and ontometal base 120 but not routing line 136, bumped terminal 138, filler 154and plated contact 164. The liquid resin is compliant enough at roomtemperature to conform to virtually any shape. Therefore, the liquidresin flows over and covers a portion of metal base 120 but remainsspaced from routing line 136, bumped terminal 138, cavity 146, filler154 and plated contact 164.

FIGS. 16A, 16B and 16C are cross-sectional, top and bottom views,respectively, of chip 110 mechanically attached to metal base 120,routing line 136, bumped terminal 138, filler 154 and plated contact 164by adhesive 166.

Adhesive 166 contacts and extends between chip 110 and metal base 120but remains spaced from routing line 136, bumped terminal 138, cavity146, filler 154 and plated contact 164. Surface 112 of chip 110 facesupwardly and away from metal base 120 and is exposed, and surface 114 ofchip 110 faces downwardly and towards metal base 120 and is covered byadhesive 166. Chip 110 and metal base 120 do not contact one another,and chip 110 and routing line 136 do not contact one another.

Adhesive 166 is sandwiched between chip 110 and metal base 120 usingrelatively low pressure from a pick-up head that places chip 110 onadhesive 166, holds chip 110 against adhesive 166 for 5 seconds and thenreleases chip 110. The pick-up head is heated to a relatively lowtemperature such as 150° C., and adhesive 166 receives heat from thepick-up head transferred through chip 110. As a result, adhesive 166proximate to chip 110 is partially polymerized (B stage) and forms a gelbut is not fully cured, and adhesive 166 that is partially polymerizedprovides a loose mechanical bond between chip 110 and metal base 120.

Chip 110 and metal base 120 are positioned relative to one another sothat chip 110 is disposed within the periphery of adhesive 166, androuting line 136, bumped terminal 138, filler 154 and plated contact 164are disposed outside the periphery of chip 110. Chip 110 and metal base120 can be aligned using an automated pattern recognition system.

Thereafter, the structure is placed in an oven and adhesive 166 is fullycured (C stage) at relatively low temperature in the range of 200 to250° C. to form a solid adhesive insulative thermosetting polyimidelayer that contacts and is sandwiched between and mechanically attacheschip 110 and metal base 120. Adhesive 166 is 30 microns thick betweenchip 110 and metal base 120.

At this stage, metal base 120 covers and extends downwardly beyond chip110, routing line 136, bumped terminal 138, filler 154, plated contact164 and adhesive 166, routing line 136 is disposed downwardly beyond andoutside the periphery of chip 110 and extends laterally beyond bumpedterminal 138 and filler 154 towards chip 110, bumped terminal 138 isdisposed outside the periphery of chip 110 and extends downwardly beyondchip 110, routing line 136 and filler 154, cavity 146 faces upwardly andextends downwardly beyond chip 110 and routing line 136, filler 154extends upwardly beyond routing line 136 and bumped terminal 138 anddownwardly beyond chip 110 and routing line 136, and adhesive 166extends downwardly beyond chip 110. Furthermore, chip 110 remainselectrically isolated from routing line 136.

FIGS. 17A, 17B and 17C are cross-sectional, top and bottom views,respectively, of connection joint 168 formed on pad 116 and platedcontact 164.

Connection joint 168 is a gold wire bond that is ball bonded to pad 116and then wedge bonded to plated contact 164. The gold wire between theball bond and the wedge bond has a thickness of 25 microns. Thus,connection joint 168 contacts and electrically connects pad 116 andplated contact 164, and consequently, electrically connects pad 116 tometal base 120, routing line 136, bumped terminal 138 and filler 154.Furthermore, connection joint 168 extends within and outside theperiphery of chip 110, extends upwardly beyond chip 110 by 100 micronsand is spaced from metal base 120, routing line 136, bumped terminal 138and filler 154.

FIGS. 18A, 18B and 18C are cross-sectional, top and bottom views,respectively, of encapsulant 170 formed on chip 110, routing line 136,bumped terminal 138, filler 154, plated contact 164, adhesive 166 andconnection joint 168.

Encapsulant 170 is deposited by transfer molding. Transfer molding isthe most popular chip encapsulation method for essentially all plasticpackages. Generally speaking, transfer molding involves formingcomponents in a closed mold from a molding compound that is conveyedunder pressure in a hot, plastic state from a central reservoir calledthe transfer pot through a tree-like array of runners and gates intoclosed cavities. Molding compounds are well-known in the art.

The preferred transfer molding system includes a preheater, a mold, apress and a cure oven. The mold includes an upper mold section and alower mold section, also called “platens” or “halves” which define themold cavities. The mold also includes the transfer pot, runners, gatesand vents. The transfer pot holds the molding compound. The runners andgates provide channels from the transfer pot to the cavities. The gatesare placed near the entrances of the cavities and are constricted tocontrol the flow and injection velocity of the molding compound into thecavities and to facilitate removal of the solidified molding compoundafter molding occurs. The vents allow trapped air to escape but aresmall enough to permit only a negligible amount of the molding compoundto pass through them.

The molding compound is initially in tablet form. The preheater applieshigh-frequency energy to preheat the molding compound to a temperaturein the range of 50 to 100° C. The preheated temperature is below thetransfer temperature and therefore the preheated molding compound is notin a fluid state. In addition, the structure is placed in one of themold cavities, and the press operates hydraulically to close the moldand seal the mold cavities by clamping together the upper and lower moldsections. Guide pins ensure proper mating of the upper and lower moldsections at the parting line. In addition, the mold is heated to atransfer temperature in the range of 150 to 250° C. by insertingelectric heating cartridges in the upper and lower mold sections.

After closing the mold, the preheated molding compound in tablet form isplaced in the transfer pot. Thereafter, a transfer plunger appliespressure to the molding compound in the transfer pot. The pressure is inthe range of 10 to 100 kgf/cm² and preferably is set as high as possiblewithout introducing reliability problems. The combination of heat fromthe mold and pressure from the transfer plunger converts the moldingcompound in the transfer pot into a fluid state. Furthermore, thepressure from the transfer plunger forces the fluid molding compoundthrough the runners and the gates into the mold cavities. The pressureis maintained for a certain optimum time to ensure that the moldingcompound fills the cavities.

The lower mold section contacts and makes sealing engagement with and isgenerally flush with metal base 120. However, the upper mold section isspaced from connection joint 168 by 120 microns. As a result, themolding compound contacts the exposed portions of the chip 110, metalbase 120, routing line 136, filler 154, plated contact 164, adhesive 166and connection joint 168 in the cavity. After 1 to 3 minutes at thetransfer temperature, the molding compound polymerizes and is partiallycured in the mold.

Once the partially cured molding compound is resilient and hard enoughto withstand ejection forces without significant permanent deformation,the press opens the mold, ejector pins remove the molded structure fromthe mold, and excess molding compound attached to the molded structurethat solidified in the runners and the gates is trimmed and removed. Themolded structure is then loaded into a magazine and postcured in thecuring oven for 4 to 16 hours at a temperature somewhat lower than thetransfer temperature but well above room temperature to completely curethe molding compound.

The molding compound is a multi-component mixture of an encapsulatingresin with various additives. The principal additives include curingagents (or hardeners), accelerators, inert fillers, coupling agents,flame retardants, stress-relief agents, coloring agents and mold-releaseagents. The encapsulating resin provides a binder, the curing agentprovides linear/cross-polymerization, the accelerator enhances thepolymerization rate, the inert filler increases thermal conductivity andthermal shock resistance and reduces the thermal coefficient ofexpansion, resin bleed, shrinkage and residual stress, the couplingagent enhances adhesion to the structure, the flame retardant reducesflammability, the stress-relief agent reduces crack propagation, thecoloring agent reduces photonic activity and device visibility, and themold-release agent facilitates removal from the mold.

Encapsulant 170 contacts and covers chip 110, metal base 120, routingline 136, filler 154, plated contact 164, adhesive 166 and connectionjoint 168. More particularly, encapsulant 170 contacts surface 112 andthe outer edges of chip 110, but is spaced from surface 114 of chip 110(due to adhesive 166). Furthermore encapsulant 170 covers but is spacedfrom bumped terminal 138 (due to filler 154).

Encapsulant 170 is a solid adherent compressible protective layer thatprovides environmental protection such as moisture resistance andparticle protection for chip 110 as well as mechanical support forrouting line 136, bumped terminal 138 and filler 154. Furthermore, chip110 is embedded in encapsulant 170.

Encapsulant 170 includes opposing surfaces 172 and 174. Surface 172faces upwardly, and surface 174 faces downwardly. Encapsulant 170extends upwardly beyond chip 110, routing line 136, bumped terminal 138,filler 154, plated contact 164, adhesive 166 and connection joint 168,has a thickness of 400 microns and extends 120 microns upwardly beyondconnection joint 168. Encapsulant 170 also extends into cavity 146, andfiller 154 and encapsulant 170 fill cavity 146.

FIGS. 19A, 19B and 19C are cross-sectional, top and bottom views,respectively, of the structure after metal base 120 is removed.

Metal base 120 is removed by applying a blanket back-side wet chemicaletch. For instance, the bottom spray nozzle can spray the wet chemicaletch on metal base 120 while the top spray nozzle is deactivated, or thestructure can be dipped in the wet chemical etch since encapsulant 170provides front-side protection. The wet chemical etch is highlyselective of copper with respect to nickel, polyimide and the moldingcompound, and therefore, highly selective of metal base 120 with respectto the nickel layer of routing line 136 and bumped terminal 138,adhesive 166 and encapsulant 170. Furthermore, the nickel layer ofrouting line 136 and bumped terminal 138 protects the underlying copperlayer of routing line 136 and bumped terminal 138 from the wet chemicaletch. Therefore, no appreciable amount of routing line 136, bumpedterminal 138, adhesive 166 or encapsulant 170 is removed. Furthermore,chip 110, filler 154, plated contact 164 and connection joint 168 arenot exposed to the wet chemical etch.

The wet chemical etch removes metal base 120. As a result, the wetchemical etch eliminates contact area between metal base 120 and routingline 136, between metal base 120 and bumped terminal 138, between metalbase 120 and adhesive 166 and between metal base 120 and encapsulant170, and exposes routing line 136, bumped terminal 138, adhesive 166 andencapsulant 170 without exposing chip 110, filler 154, plated contact166 and connection joint 168.

A suitable wet chemical etch can be provided by a solution containingalkaline ammonia. The optimal etch time for removing metal base 120without excessively exposing routing line 136 and bumped terminal 138 tothe wet chemical etch can be established through trial and error.

Encapsulant 170 provides mechanical support for routing line 136, bumpedterminal 138 and filler 154 and reduces mechanical strain on adhesive166, which is particularly useful after metal base 120 is removed.Encapsulant 170 protects routing line 136, bumped terminal 138 andfiller 154 from mechanical damage by the wet chemical etch andsubsequent cleaning steps (such as rinsing in distilled water and airblowing). For instance, encapsulant 170 absorbs physical force of thewet chemical etch and cleaning steps that might otherwise separate chip110 and routing line 136. Thus, encapsulant 170 improves structuralintegrity and allows the wet chemical etch and subsequent cleaning stepsto be applied more vigorously, thereby improving manufacturingthroughput.

FIGS. 20A, 20B and 20C are cross-sectional, top and bottom views,respectively, of insulative base 176 formed on routing line 136, bumpedterminal 138, adhesive 166 and encapsulant 170.

Insulative base 176 is initially an epoxy in paste form that includes anepoxy resin, a curing agent, an accelerator and a filler. The filler isan inert material, such as silica (powdered fused quartz), that improvesthermal conductivity, thermal shock resistance, and thermal coefficientof expansion matching. The epoxy paste is blanketly deposited on routingline 136, bumped terminal 138, adhesive 166 and encapsulant 170, andthen the epoxy paste is cured or hardened at a relatively lowtemperature in the range of 100 to 250° C. to form a solid adherentinsulator that provides a protective seal for routing line 136.

Insulative base 176 contacts and covers and extends downwardly beyondrouting line 136, bumped terminal 138, adhesive 166 and encapsulant 170,covers and extends downwardly beyond and is spaced from chip 110, filler154, plated contact 164 and connection joint 168, and has a thickness of160 microns. Thus, insulative base 176 extends downwardly beyond bumpedterminal 138 by 20 microns and bumped terminal 138 is unexposed.

For convenience of illustration, insulative base 176 is shown below chip110 to retain a single orientation throughout the figures for ease ofcomparison between the figures, although in this step the structurewould be inverted so that gravitational force would assist the epoxypaste deposition.

FIGS. 21A, 21B and 21C are cross-sectional, top and bottom views,respectively, of the structure after a lower portion of insulative base176 is removed.

The lower portion of insulative base 176 is removed by grinding. Inparticular, a rotating diamond sand wheel and distilled water areapplied to the back-side of insulative base 176. Initially, the diamondsand wheel grinds only insulative base 176. As the grinding continues,insulative base 176 becomes thinner as the grinded surface migratesupwardly. Eventually the diamond sand wheel contacts bumped terminal138, and as a result, begins to grind bumped terminal 138 as well. Asthe grinding continues, bumped terminal 138 and insulative base 176become thinner as their grinded surfaces migrate upwardly. Eventuallythe diamond sand wheel contacts filler 154, and as a result, begins togrind filler 154 as well. As the grinding continues, bumped terminal138, filler 154 and insulative base 176 become thinner as their grindedsurfaces migrate upwardly. The grinding continues until bumped terminal138, filler 154 and insulative base 176 have the desired thickness, andthen halts before it reaches chip 110, routing line 136, plated contact164, adhesive 166, connection joint 168 or encapsulant 170. Thereafter,the structure is rinsed in distilled water to remove contaminants.

Bumped terminal 138, filler 154 and insulative base 176 extenddownwardly beyond routing line 136 by 100 microns after the grindingoperation. Thus, the grinding removes a 40 micron thick lower portion ofbumped terminal 138, a 20 micron thick lower portion of filler 154 and a60 micron thick lower portion of insulative base 176. Moreover, thegrinding operation exposes bumped terminal 138 and filler 154.

Bumped terminal 138, cavity 146, filler 154 and insulative base 176 arelaterally aligned with one another at lateral surface 178 that facesdownwardly. Thus, lateral surface 178 is an exposed planarizedhorizontal surface that faces downwardly and includes bumped terminal138, cavity 146, filler 154 and insulative base 176. Furthermore, bumpedterminal 138 forms a ring at lateral surface 178, is adjacent to filler154 at lateral surface 178, encircles and surrounds filler 154 and onlyfiller 154 at lateral surface 178 and has a smaller surface area thanfiller 154 at lateral surface 178, filler 154 forms a circle at lateralsurface 178, and insulative base 176 surrounds and is adjacent to bumpedterminal 138 at lateral surface 178.

The copper layer of routing line 136 and bumped terminal 138 is adjacentto cavity 146, contacts filler 154 and extends upwardly beyond thenickel layer of routing line 136 and bumped terminal 138, and the nickellayer of routing line 136 and bumped terminal 138 is spaced from cavity146 and filler 154. In addition, the copper and nickel layers arelaterally aligned with cavity 146, filler 154, insulative base 176 andone another at lateral surface 178. Furthermore, the nickel layer formsa ring that contacts and is adjacent to insulative base 176 and thecopper layer, is spaced from filler 154 and encircles the copper layerat lateral surface 178, and the copper layer forms a ring that contactsand is adjacent to filler 154 and the copper layer, is spaced frominsulative base 176 and encircles filler 154 at lateral surface 178.

Chip 110 remains embedded in encapsulant 170 and extends upwardly beyondrouting line 136, bumped terminal 138, filler 154, adhesive 166 andinsulative base 176, routing line 136 is disposed outside the peripheryof chip 110 and downwardly beyond chip 110, plated contact 164 andconnection joint 168 and extends laterally beyond bumped terminal 138and filler 154 towards chip 110, bumped terminal 138 is disposed outsidethe periphery of chip 110 and downwardly beyond chip 110, routing line136, plated contact 164 and connection joint 168 and extends downwardlybeyond encapsulant 170, filler 154 is disposed outside the periphery ofchip 110, extends upwardly beyond routing line 136, bumped terminal 138,plated contact 164, adhesive 166 and insulative base 176 and extendsdownwardly beyond chip 110, routing line 136, plated contact 164,adhesive 166, connection joint 168 and encapsulant 170, adhesive 166extends downwardly beyond chip 110, connection joint 168 extends withinand outside the periphery of chip 110, encapsulant 170 covers chip 110,routing line 136, bumped terminal 138, filler 154, plated contact 164,adhesive 166, connection joint 168 and insulative base 176 in the upwarddirection, and insulative base 176 extends downwardly beyond chip 110,routing line 136, plated contact 164, adhesive 166, connection joint 168and encapsulant 170. In addition, routing line 136 remains unexposed,bumped terminal 138 and filler 154 are exposed at lateral surface 178and filler 154 and encapsulant 170 fill cavity 146.

Cavity 146 extends through bumped terminal 138 and is not covered bybumped terminal 138 in the upward or downward directions. In otherwords, cavity 146 extends through bumped terminal 138 in the upward anddownward directions. Thus, the grinding operation converts cavity 146from a blind via relative to bumped terminal 138 (that extends throughbumped terminal 138 in only the upward direction) into a through-holerelative to bumped terminal 138 (that extends through bumped terminal138 in the upward and downward directions).

Cavity 146 includes upper and lower opposing ends and curved taperedsidewalls therebetween. The upper end of cavity 146 is adjacent tobumped terminal 138 and faces upwardly, the lower end of cavity 146 isadjacent to bumped terminal 138 and faces downwardly, and the curvedtapered sidewalls of cavity 146 are adjacent to the upper and lower endsof cavity 146 and slant inwardly towards the lower end of cavity 146.Thus, cavity 146 has a diameter that decreases as cavity 146 extends inthe downward direction. Cavity 146 continues to extend across a majorityof the height and diameter of bumped terminal 138 and filler 154, andalso extends across the entire height of bumped terminal 138 (in theupward and downward directions).

The upper and lower ends of cavity 146 are vertically aligned withbumped terminal 138, enlarged annular portion 144 and one another. Thus,the lower end of cavity 146 is concentrically disposed within thesurface area of bumped terminal 138, enlarged annular portion 144,filler 154 and the upper end of cavity 146. In addition, bumped terminal138, filler 154 and the upper end of cavity 146 have a surface area thatis at least 20 percent larger than the surface area of the lower end ofcavity 146. Moreover, the lower end of cavity 146 and the lower surface(surface 158) of filler 154 are co-extensive and have identical size,shape and location.

FIGS. 22A, 22B and 22C are cross-sectional, top and bottom views,respectively, of plated terminal 180 formed on bumped terminal 138 andfiller 154.

Plated terminal 180 is electrolessly plated on bumped terminal 138 andfiller 154. Plated terminal 180 is composed of a nickel layerelectrolessly plated on bumped terminal 138 and filler 154 and a goldlayer electrolessly plated on the nickel layer. The nickel layercontacts and is sandwiched between bumped terminal 138 and the goldlayer and between filler 154 and the gold layer, and the gold layer isspaced from bumped terminal 138 and filler 154 and exposed. Forconvenience of illustration, the nickel and gold layers are shown as asingle layer.

The structure is dipped in an activator solution such as dilutepalladium chloride of approximately 0.1 grams of palladium chloride and5 cubic centimeters of hydrochloric acid per liter of water to renderbumped terminal 138 and filler 154 catalytic to electroless nickel, thenthe structure is rinsed in distilled water to remove the palladium fromencapsulant 170 and insulative base 176.

The structure is then submerged in an electroless nickel platingsolution such as Enthone Enplate NI-424 at 85° C. Preferred nickelplating solutions include nickel-sulfate and nickel-chloride and have apH of about 9.5 to 10.5. A higher nickel concentration provides a fasterplating rate but reduces the stability of the solution. The amount ofchelating agents or ligands in the solution depends on the nickelconcentration and their chemical structure, functionality and equivalentweight. Most of the chelating agents used in electroless nickel platingsolutions are hydroxy organic acids which form one or more water solublenickel ring complexes. These complexes reduce the free nickel ionconcentration, thereby increasing the stability of the solution whileretaining a reasonably fast plating rate. Generally, the higher thecomplex agent concentration, the slower the plating rate. In addition,the pH of the solution and the plating rate continually decrease as theelectroless plating continues due to hydrogen ions being introduced intothe solution as a byproduct of the nickel reduction. Accordingly, thesolution is buffered to offset the effects of the hydrogen ions.Suitable buffering agents include sodium or potassium salts of mono anddibasic organic acids. Finally, those skilled in the art will understandthat electroless nickel plating solutions do not deposit pure elementalnickel since a reducing agent such as H₂PO₂ will naturally decomposeinto the electrolessly plated nickel. Therefore, those skilled in theart will understand that electrolessly plated nickel refers to a nickelcompound that is mostly nickel but not pure elemental nickel.

Bumped terminal 138 and filler 154 are catalytic to electroless nickel.Furthermore, encapsulant 170 and insulative base 176 are not catalyticto electroless nickel and therefore a plating mask is not necessary. Asa result, plated terminal 180 plates on bumped terminal 138 and filler154.

The electroless nickel plating operation continues until plated terminal180 is 4 microns thick. At this point, plated terminal 180 is primarilynickel and contain about 4 to 9 weight percentage phosphorus.

Thereafter, the structure is removed from the electroless nickel platingsolution and briefly submerged in an electroless gold plating solutionsuch as is MacDermid PLANAR™ at 70° C. Plated terminal 180 includes anexposed nickel surface layer and therefore is catalytic to electrolessgold. Furthermore, encapsulant 170 and insulative base 176 are notcatalytic to electroless gold and therefore a plating mask is notnecessary. As a result, the gold deposits on the nickel surface layer.The gold electroless plating operation continues until the gold surfacelayer is 0.5 microns thick. Thereafter, the structure is removed fromthe electroless gold plating solution and rinsed in distilled water.

Plated terminal 180 contacts and is electrically connected to bumpedterminal 138 and filler 154 and extends downwardly beyond bumpedterminal 138, filler 154 and insulative base 176. Thus, plated terminal180 is spaced from and extends downwardly beyond chip 110, routing line136, plated contact 164, adhesive 166, connection joint 168 andencapsulant 170. Moreover, plated terminal 180 provides a robust,permanent electrical connection to bumped terminal 138 and filler 154that protrudes downwardly from bumped terminal 138 and filler 154 and isexposed. Plated terminal 180 includes a buried nickel layer and a goldsurface layer. The buried nickel layer provides the primary mechanicaland electrical connection to bumped terminal 138 and filler 154, and thegold surface layer provides a wettable surface to facilitate solderreflow.

Conductive trace 182 includes routing line 136, bumped terminal 138,filler 154, plated contact 164 and plated terminal 180. Conductive trace182 is electrically connected to pad 116 by connection joint 168 and isadapted for providing horizontal and vertical routing between pad 116and a next level assembly.

FIGS. 23A, 23B and 23C are cross-sectional, top and bottom views,respectively, of the structure after cutting encapsulant 170 andinsulative base 176 with an excise blade to singulate the assembly fromother assemblies.

At this stage, the manufacture of semiconductor chip assembly 198 thatincludes chip 110, routing line 136, bumped terminal 138, filler 154,plated contact 164, adhesive 166, connection joint 168, encapsulant 170,insulative base 176 and plated terminal 180 can be considered complete.

Routing line 136 is mechanically coupled to chip 110 by adhesive 166,and is electrically coupled to chip 110 by connection joint 168. Routingline 136 and connection joint 168 provide horizontal fan-out routingbetween pad 116 and external circuitry, and bumped terminal 138, filler154 and plated terminal 180 provide vertical routing between pad 116 andexternal circuitry. Encapsulant 170 and insulative base 176 providemechanical support and environmental protection for the assembly.Encapsulant 170 covers chip 110 and conductive trace 182 in the upwarddirection. Lateral surface 178 is an exposed major surface of theassembly. Although bumped terminal 138 and filler 154 are not exposed,and are overlapped by insulative base 176 and plated terminal 180 in thedownward direction, bumped terminal 138 and filler 154 are not coveredin the downward direction by encapsulant 170, insulative base 176 or anyother insulative material of the assembly.

The semiconductor chip assembly is a single-chip first-level packagethat is devoid of a printed circuit board.

The semiconductor chip assembly includes other conductive tracesembedded in encapsulant 170, and only a single conductive trace 182 isshown for convenience of illustration. The conductive traces are spacedand separated and electrically isolated from one another. The conductivetraces each include a respective routing line, bumped terminal, filler,plated contact and plated terminal. The conductive traces are eachelectrically connected to a respective pad on chip 110 by a respectiveconnection joint. The conductive traces each provide horizontal fan-outrouting and vertical routing for their respective pads. Furthermore, theconductive traces each include a downwardly protruding plated terminalto provide a land grid array (LGA) package.

Chip 110 is designed with the pads electrically isolated from oneanother. However, the corresponding routing lines are initiallyelectroplated on metal base 120 and electrically connected to oneanother by metal base 120. Furthermore, the connection jointselectrically connect the routing lines and the corresponding pads,thereby electrically connecting the pads with one another. Thereafter,once metal base 120 is removed, the routing lines are electricallyisolated from one another, and therefore, the pads return to beingelectrically isolated from one another.

Advantageously, there is no plating bus or related circuitry that needbe disconnected or severed from the conductive traces after the metalbase removed.

FIGS. 24A, 24B and 24C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with asecond embodiment of the present invention. In the second embodiment,the chip is flip-chip bonded. For purposes of brevity, any descriptionin the first embodiment is incorporated herein insofar as the same isapplicable, and the same description need not be repeated. Likewise,elements of the second embodiment similar to those in the firstembodiment have corresponding reference numerals indexed at two-hundredrather than one-hundred. For instance, chip 210 corresponds to chip 110,routing line 236 corresponds to routing line 136, etc.

Connection joint 268 is initially a solder bump deposited on pad 216.The solder bump has a hemispherical shape and a diameter of 100 microns.

Routing line 236 extends within and outside the periphery of chip 210.Thus, the elongated routing portion (corresponding to elongated routingportion 142) is lengthened. This is accomplished by a slight adjustmentto the electroplating operation previously described for routing line136. In particular, the photoresist layer (corresponding to photoresistlayer 132) is patterned to reshape the opening for routing line 236, andtherefore routing line 236 is lengthened relative to routing line 136.Furthermore, the plated contact (corresponding to plated contact 164) isomitted.

Chip 210 is positioned such that surface 212 faces downwardly, surface214 faces upwardly, routing line 236 extends laterally across pad 216,and connection joint 268 contacts and is sandwiched between pad 216 androuting line 236. Thereafter, heat is applied to reflow connection joint268, and then the heat is removed and connection joint 268 cools andsolidifies into a hardened solder joint that mechanically attaches andelectrically connects pad 216 and routing line 236. Connection joint 268exhibits localized wetting and does not collapse, and chip 210 remainsspaced from routing line 236.

Thereafter, adhesive 266 is dispensed into and underfills the open gapbetween chip 210 and the metal base (corresponding to metal base 120),and then adhesive 266 is cured. As a result, adhesive 266 contacts andis sandwiched between chip 210 and the metal base, contacts connectionjoint 268 and is spaced from pad 216. Thus, adhesive 266 issignificantly thicker than adhesive 166. A suitable underfill adhesiveis Namics U8443.

Thereafter, encapsulant 270, insulative base 276 and plated terminal 280are formed.

Semiconductor chip assembly 298 includes chip 210, routing line 236,bumped terminal 238, filler 254, adhesive 266, connection joint 268,encapsulant 270, insulative base 276 and plated terminal 280.

FIGS. 25A, 25B and 25C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with athird embodiment of the present invention. In the third embodiment, theconnection joint is electroplated. For purposes of brevity, anydescription in the first embodiment is incorporated herein insofar asthe same is applicable, and the same description need not be repeated.Likewise, elements of the third embodiment similar to those in the firstembodiment have corresponding reference numerals indexed atthree-hundred rather than one-hundred. For instance, chip 310corresponds to chip 110, routing line 336 corresponds to routing line136, etc.

Pad 316 is treated to accommodate an electroplated copper connectionjoint by forming a nickel surface layer on the aluminum base. Forinstance, chip 310 is dipped in a zinc solution to deposit a zinc layeron the aluminum base. This step is commonly known as zincation.Preferably, the zinc solution contains about 150 grams/liter of NaOH, 25grams/liter of ZnO, and 1 gram/liter of NaNO₃, as well as tartaric acidto reduce the rate at which the aluminum base dissolves. Thereafter, thenickel surface layer is electrolessly deposited on the zincated aluminumbase. A suitable electroless nickel plating solution is Enthone EnplateNI-424 at 85° C.

Routing line 336 extends within and outside the periphery of chip 310.Thus, the elongated routing portion (corresponding to elongated routingportion 142) is lengthened. This is accomplished by a slight adjustmentto the electroplating operation previously described for routing line136. In particular, the photoresist layer (corresponding to photoresistlayer 132) is patterned to reshape the opening for routing line 336, andtherefore routing line 336 is lengthened relative to routing line 136.

The metal base (corresponding to metal base 120) is etched to form aback-side recess (not shown), the plated contact (corresponding toplated contact 164) is omitted, and adhesive 366 is deposited on themetal base and routing line 336.

Chip 310 is inverted and positioned such that surface 312 facesdownwardly, surface 314 faces upwardly, adhesive 366 contacts and issandwiched between pad 316 and routing line 336, and routing line 336partially overlaps pad 316. Thereafter, encapsulant 370 is formed, andthen the metal base is etched again to convert the back-side recess intoa slot (not shown) that extends through the metal base, exposes adhesive366 and is vertically aligned with pad 316.

Thereafter, through-hole 384 is formed in adhesive 366 that exposes pad316. Through-hole 384 is formed by applying a suitable etch that ishighly selective of adhesive 366 with respect to pad 316 and routingline 336. In this instance, a selective TEA CO₂ laser etch is applied.The laser is directed at and vertically aligned with and centeredrelative to pad 316. The laser has a spot size of 70 microns, and pad316 has a length and width of 100 microns. As a result, the laserstrikes pad 316 and portions of routing line 336 and adhesive 366 thatextend within the periphery of pad 316, and ablates adhesive 366. Thelaser drills through and removes a portion of adhesive 366. However,portions of adhesive 366 that extend across the peripheral edges of pad316 are outside the scope of the laser and remain intact. Likewise,routing line 336 shields a portion of adhesive 366 from the laser etch,and a portion of adhesive 366 sandwiched between pad 316 and routingline 336 remains intact. The laser etch is anisotropic, and thereforelittle or none of adhesive 366 sandwiched between pad 316 and routingline 336 is undercut or removed. Through-hole 384 may slightly undercutadhesive 366 between pad 316 and routing line 336 and have a diameterthat is slightly larger than 70 microns due to the beam angle of thelaser, the thermal effects of the laser, and/or the isotropic nature ofan oxygen plasma or wet chemical cleaning step. For convenience ofexplanation, this slight undercut and enlargement is ignored. However,through-hole 384 is formed without damaging chip 310 or routing line 336and does not extend into chip 310.

Thereafter, a brief cleaning step can be applied to remove oxides anddebris that may be present on the exposed portions of pad 316 androuting line 336. For instance, a brief oxygen plasma cleaning step canbe applied to the structure. Alternatively, a brief wet chemicalcleaning step using a solution containing potassium permanganate can beapplied to the structure. In either case, the cleaning step cleans theexposed portions of pad 316 and routing line 336 without damaging thestructure.

Thereafter, connection joint 368 is formed by an electroplatingoperation. Initially, the metal base is connected to a plating bus (notshown), current is applied to the plating bus from an external powersource, and the structure is submerged in an electrolytic copper platingsolution such as Sel-Rex CUBATH M™ at room temperature. As a result,connection joint 368 electroplates on the exposed portions of the metalbase. In addition, since the plating bus provides the current to themetal base, which in turn provides the current to routing line 336,connection joint 368 electroplates on the exposed portions of routingline 336 in through-hole 384. At the initial stage, since adhesive 366is an electrical insulator and pad 316 is not connected to the platingbus, connection joint 368 does not electroplate on pad 316 and is spacedfrom pad 316. However, as the copper electroplating continues,connection joint 368 continues to plate on routing line 336, extendsthrough adhesive 366 and contacts pad 316. As a result, pad 316 isconnected to the plating bus by the metal base, routing line 336 andconnection joint 368, and therefore connection joint 368 begins toelectroplate on pad 316 as well. The copper electroplating continuesuntil connection joint 368 has the desired thickness. Thereafter, thestructure is removed from the electrolytic copper plating solution andrinsed in distilled water to remove contaminants.

Thereafter, insulative plug 386 is formed on adhesive 366 and connectionjoint 368 and disposed within the slot, and then insulative base 376 andplated terminal 380 are formed.

Semiconductor chip assembly 398 includes chip 310, routing line 336,bumped terminal 338, filler 354, adhesive 366, connection joint 368,encapsulant 370, insulative base 376, plated terminal 380 and insulativeplug 386.

FIGS. 26A, 26B and 26C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with afourth embodiment of the present invention. In the fourth embodiment,the connection joint is electrolessly plated. For purposes of brevity,any description in the first embodiment is incorporated herein insofaras the same is applicable, and the same description need not berepeated. Likewise, elements of the fourth embodiment similar to thosein the first embodiment have corresponding reference numerals indexed atfour-hundred rather than one-hundred. For instance, chip 410 correspondsto chip 110, routing line 436 corresponds to routing line 136, etc.

Pad 416 is treated to include a nickel surface layer in the same manneras pad 316, routing line 436 is configured in the same manner as routingline 336, adhesive 466 is deposited on the metal base (corresponding tometal base 120) and routing line 436 in the same manner that adhesive366 is deposited on the metal base and routing line 336, and the platedcontact (corresponding to plated contact 164) is omitted.

Chip 410 is inverted and positioned such that surface 412 facesdownwardly, surface 414 faces upwardly, adhesive 466 contacts and issandwiched between pad 416 and routing line 436, and routing line 436partially overlaps pad 416. Thereafter, encapsulant 470 is formed, andthen the metal base is removed. Thereafter, through-hole 484 is formedin adhesive 466 and exposes pad 416. Through-hole 484 is formed in thesame manner as through-hole 384.

Thereafter, connection joint 468 is formed by an electroless platingoperation. The structure is submerged in an electroless nickel platingsolution such as Enthone Enplate NI-424 at 85° C. Pad 416 includes anexposed nickel surface layer and therefore is catalytic to electrolessnickel. Connection joint 468 plates on pad 416 and eventually contactsand electrically connects pad 416 and routing line 436 in through-hole482. The electroless nickel plating operation continues until connectionjoint 468 is about 10 microns thick. Thereafter, the structure isremoved from the electroless nickel plating solution and rinsed indistilled water.

Thereafter, insulative base 476 and plated terminal 480 are formed.

Semiconductor chip assembly 498 includes chip 410, routing line 436,bumped terminal 438, filler 454, adhesive 466, connection joint 468,encapsulant 470, insulative base 476 and plated terminal 480.

FIGS. 27A, 27B and 27C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with afifth embodiment of the present invention. In the fifth embodiment, thefiller is solder. For purposes of brevity, any description in the firstembodiment is incorporated herein insofar as the same is applicable, andthe same description need not be repeated. Likewise, elements of thefifth embodiment similar to those in the first embodiment havecorresponding reference numerals indexed at five-hundred rather thanone-hundred. For instance, chip 510 corresponds to chip 110, routingline 536 corresponds to routing line 136, etc.

Filler 554 is a solder ball that is spaced from routing line 536 anddoes not overlap routing line 536 in the upward direction, is disposedwithin the surface area of bumped terminal 538 and does not cover bumpedterminal 538 in the upward direction, fills cavity 546 and has anon-uniform thickness.

Filler 554 is initially a tin-lead ball with a spherical shape. Thetin-lead ball is dipped in flux to provide filler 554 with a fluxsurface coating that surrounds the tin-lead ball. Thereafter, filler 554is deposited on bumped terminal 538 in cavity 546 and weakly adheres tobumped terminal 538 due to the flux surface coating. Thereafter, heat isapplied to reflow filler 554. The photoresist layers (corresponding tophotoresist layers 150 and 152) and related electroplating operation forthe filler are omitted.

Semiconductor chip assembly 598 includes chip 510, routing line 536,bumped terminal 538, filler 554, plated contact 564, adhesive 566,connection joint 568, encapsulant 570, insulative base 576 and platedterminal 580.

FIGS. 28A, 28B and 28C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with asixth embodiment of the present invention. In the sixth embodiment, thefiller is laterally aligned with the encapsulant. For purposes ofbrevity, any description in the first embodiment is incorporated hereininsofar as the same is applicable, and the same description need not berepeated. Likewise, elements of the sixth embodiment similar to those inthe first embodiment have corresponding reference numerals indexed atsix-hundred rather than one-hundred. For instance, chip 610 correspondsto chip 110, routing line 636 corresponds to routing line 136, etc.

Filer 654 is composed of solder bond 654A and metal ball 654B. Solderbond 654A contacts and is sandwiched between bumped terminal 638 andmetal ball 654B, and metal ball 654B is spaced from bumped terminal 638.Furthermore, solder bond 654A has a concave, crater-like shape andextends upwardly beyond routing line 636 and bumped terminal 638 andextends within and outside cavity 646 but does not extend upwardlybeyond chip 610, and metal ball 654B is a copper ball with a sphericalshape that extends within and outside cavity 646 and extends upwardlybeyond chip 610.

Bumped terminal 638 has a diameter of 500 microns (rather than 300microns). This is accomplished by a slight adjustment to the etchingoperation previously described for recess 130 and the electroplatingoperation previously described for routing line 136 and bumped terminal138. In particular, the photoresist layer (corresponding to photoresistlayer 126) is patterned to widen the opening for the recess(corresponding to recess 130), and therefore the recess is widenedrelative to recess 130. Thereafter, the photoresist layer (correspondingto photoresist layer 132) is patterned to widen the opening for routingline 736 and bumped terminal 738 at the recess, and therefore routingline 736 is widened relative to routing line 136 at enlarged annularportion 744 relative to enlarged annular portion 144, and bumpedterminal 738 is widened relative to bumped terminal 138.

Filler 654 is formed by depositing solder paste on bumped terminal 638and into cavity 646, then depositing metal ball 654B on the solder pasteand into cavity 646, and then heating and reflowing the solder paste toform solder bond 654A. The photoresist layers (corresponding tophotoresist layers 150 and 152) and related electroplating operation forthe filler are omitted.

Thereafter, adhesive 666 is deposited on the metal base (correspondingto metal base 120), then chip 610 is attached to the metal base byadhesive 666, then connection joint 668 is formed, and then encapsulant670 is formed with a thickness of 500 microns (rather than 400 microns)and extends 50 microns upwardly beyond metal ball 654B and 220 micronsupwardly beyond connection joint 668.

Thereafter, an upper portion of encapsulant 670 is removed by grinding.In particular, a rotating diamond sand wheel and distilled water areapplied to the front-side of encapsulant 670. Initially, the diamondsand wheel grinds only encapsulant 670. As the grinding continues,encapsulant 670 becomes thinner as the grinded surface migratesdownwardly. Eventually the diamond sand wheel contacts filler 654, andas a result, begins to grind filler 654 as well. As the grindingcontinues, filler 654 and encapsulant 670 become thinner as theirgrinded surfaces migrate downwardly. The grinding continues until filler654 and encapsulant 670 have the desired thickness, and then haltsbefore it reaches chip 610, routing line 636, bumped terminal 638,cavity 646, plated contact 664, adhesive 666 or connection joint 668.Thereafter, the structure is rinsed in distilled water to removecontaminants.

Filler 654 and encapsulant 670 extend upwardly beyond connection joint668 by 70 microns after the grinding operation. Thus, the grindingremoves a 100 micron thick upper portion of filler 654 (at metal ball654B) and a 150 micron thick upper portion of encapsulant 670. Moreover,the grinding operation exposes filler 654.

Filler 654 and encapsulant 670 are laterally aligned with one another atlateral surface 677 that faces upwardly. Thus, lateral surface 677 is anexposed planarized horizontal surface that faces upwardly and includesfiller 654 and encapsulant 670. Furthermore, filler 654 forms a circleat lateral surface 677, and encapsulant 670 surrounds and is adjacent tofiller 654 at lateral surface 677.

Thereafter, the metal base is etched and removed, then insulative base676 is formed, and then bumped terminal 638, filler 654 and insulativebase 676 are grinded. Bumped terminal 638, cavity 646, filler 654 andinsulative base 676 are laterally aligned with one another at lateralsurface 678. Furthermore, bumped terminal 638 forms a ring at lateralsurface 678, surrounds and is adjacent to solder bond 654A at lateralsurface 678 and is spaced from metal ball 654B at lateral surface 678,solder bond 654A forms a ring at lateral surface 678, surrounds and isadjacent to metal ball 654B at lateral surface 678 and has a smallersurface area than metal ball 654B at lateral surface 678, and metal ball654B forms a circle at lateral surface 678.

Thereafter, plated terminal 680 is formed.

Semiconductor chip assembly 698 includes chip 610, routing line 636,bumped terminal 638, filler 654, plated contact 664, adhesive 666,connection joint 668, encapsulant 670, insulative base 676 and platedterminal 680.

FIGS. 29A, 29B and 29C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with aseventh embodiment of the present invention. In the seventh embodiment,the adhesive covers the bumped terminal and the filler. For purposes ofbrevity, any description in the first embodiment is incorporated hereininsofar as the same is applicable, and the same description need not berepeated. Likewise, elements of the seventh embodiment similar to thosein the first embodiment have corresponding reference numerals indexed atseven-hundred rather than one-hundred. For instance, chip 710corresponds to chip 110, routing line 736 corresponds to routing line136, etc.

Routing line 736 extends within and outside the periphery of chip 710,and bumped terminal 738 and filler 754 are disposed within the peripheryof chip 710. This is accomplished by a slight adjustment to the etchingoperation previously described for recess 130 and the electroplatingoperations previously described for routing line 136, bumped terminal138 and filler 154. In particular, the photoresist layer (correspondingto photoresist layer 126) is patterned to laterally shift the openingfor the recess (corresponding to recess 130), and therefore the recessis laterally shifted relative to recess 130. Thereafter, the photoresistlayer (corresponding to photoresist layer 132) is patterned to reshapethe opening for routing line 736 and bumped terminal 738, and thereforerouting line 736 is lengthened relative to routing line 136 and bumpedterminal 738 is laterally shifted relative to bumped terminal 138.Thereafter, the photoresist layer (corresponding to photoresist layer150) is patterned to laterally shift the opening for filler 754, andtherefore filler 754 is laterally shifted relative to filler 154. As aresult, bumped terminal 738, filler 754 and plated terminal 780 aredisposed within the periphery of chip 710, adhesive 766 covers bumpedterminal 738 and filler 754 and extends into cavity 746, and encapsulant770 does not extend into cavity 746. Furthermore, filler 754 andadhesive 766 fill cavity 746.

Semiconductor chip assembly 798 includes chip 710, routing line 736,bumped terminal 738, filler 754, plated contact 764, adhesive 766,connection joint 768, encapsulant 770, insulative base 776 and platedterminal 780.

FIGS. 30A, 30B and 30C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with aneighth embodiment of the present invention. In the eighth embodiment,the insulative base is recessed relative to the bumped terminal and thefiller. For purposes of brevity, any description in the first embodimentis incorporated herein insofar as the same is applicable, and the samedescription need not be repeated. Likewise, elements of the eighthembodiment similar to those in the first embodiment have correspondingreference numerals indexed at eight-hundred rather than one-hundred. Forinstance, chip 810 corresponds to chip 110, routing line 836 correspondsto routing line 136, etc.

Insulative base 876 is formed without a filler. As a result, insulativebase 876 is more susceptible to plasma etching than insulative base 176.After the grinding operation, a blanket back-side plasma etch is appliedto the structure. The plasma etch is highly selective of epoxy withrespect to copper and nickel, and therefore, highly selective ofinsulative base 876 with respect to bumped terminal 838 and filler 854.The plasma etch removes a 20 micron thick lower portion of insulativebase 876. As a result, bumped terminal 838 and filler 854 extenddownwardly beyond insulative base 876, and thus insulative base 876 isrecessed relative to bumped terminal 838 and filler 854 in the downwarddirection.

Thereafter, plated terminal 880 is formed.

Semiconductor chip assembly 898 includes chip 810, routing line 836,bumped terminal 838, filler 854, plated contact 864, adhesive 866,connection joint 868, encapsulant 870, insulative base 876 and platedterminal 880.

FIGS. 31A, 31B and 31C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with aninth embodiment of the present invention. In the ninth embodiment, theassembly includes a solder terminal. For purposes of brevity, anydescription in the first embodiment is incorporated herein insofar asthe same is applicable, and the same description need not be repeated.Likewise, elements of the ninth embodiment similar to those in the firstembodiment have corresponding reference numerals indexed at nine-hundredrather than one-hundred. For instance, chip 910 corresponds to chip 110,routing line 936 corresponds to routing line 136, etc.

Solder terminal 988 is initially a tin-lead ball with a spherical shape.The tin-lead ball is dipped in flux to provide solder terminal 988 witha flux surface coating that surrounds the tin-lead ball. Thereafter, thestructure is inverted so that plated terminal 980 faces upwardly, andsolder terminal 988 is deposited on plated terminal 980. Solder terminal988 weakly adheres to plated terminal 980 due to the flux surfacecoating. Thereafter, heat is applied to reflow solder terminal 988.Plated terminal 980 contains a gold surface layer that provides awettable surface for solder reflow. As a result, solder terminal 988wets plated terminal 980. The heat is then removed and solder terminal988 cools and solidifies.

Solder terminal 988 contacts and is electrically connected to platedterminal 980 and extends downwardly beyond insulative base 976 andplated terminal 980. Thus, solder terminal 988 provides a reflowableelectrical connection to plated terminal 980, and the assembly is a ballgrid array (BGA) package.

Semiconductor chip assembly 998 includes chip 910, routing line 936,bumped terminal 938, filler 954, plated contact 964, adhesive 966,connection joint 968, encapsulant 970, insulative base 976, platedterminal 980 and solder terminal 988.

FIGS. 32A, 32B and 32C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with atenth embodiment of the present invention. In the tenth embodiment, theassembly is a multi-chip package. For purposes of brevity, anydescription in the first embodiment is incorporated herein insofar asthe same is applicable, and the same description need not be repeated.Likewise, elements of the tenth embodiment similar to those in the firstembodiment have corresponding reference numerals indexed at one-thousandrather than one-hundred. For instance, chip 1010 corresponds to chip110, routing line 1036 corresponds to routing line 136, etc.

Plated contact 1064 is lengthened. This is accomplished by a slightadjustment to the electroplating operation previously described forplated contact 164. In particular, the photoresist layer (correspondingto photoresist layer 160) is patterned to lengthen the opening forplated contact 1064, and therefore plated contact 1064 is lengthenedrelative to plated contact 164.

Chip 1010 is mechanically attached to routing line 1036, bumped terminal1038, filler 1054 and plated contact 1064 by adhesive 1066 andelectrically connected to routing line 1036 by connection joint 1068.

Thereafter, adhesive 1067 is deposited as a spacer paste that includessilicon spacers on chip 1010, then chip 1011 (which includes pad 1017and is essentially identical to chip 1010) is placed on adhesive 1067such that adhesive 1067 contacts and is sandwiched between chips 1010and 1011, and then the structure is placed in an oven and adhesive 1067is fully cured (C stage) at relatively low temperature in the range of100 to 200° C. to form a solid adhesive insulative layer thatmechanically attaches chips 1010 and 1011. Adhesive 1067 is 100 micronsthick between chips 1010 and 1011, and chips 1010 and 1011 are spacedand separated from and vertically aligned with one another. A suitablespacer paste is Hysol QMI 500.

Thereafter, chip 1011 is electrically connected to routing line 1036 byconnection joint 1069 in the same manner that chip 1010 is electricallyconnected to routing line 1036 by connection joint 1068.

Thereafter, encapsulant 1070 with a thickness of 700 microns (ratherthan 400 microns) is formed so that encapsulant 1070 contacts and coverschips 1010 and 1011, routing line 1036, bumped terminal 1038, filler1054, adhesives 1066 and 1067 and connection joints 1068 and 1069, andthen insulative base 1076 and plated terminal 1080 are formed.

The semiconductor chip assembly is a multi-chip first-level package.Chips 1010 and 1011 are embedded in encapsulant 1070. Furthermore, anelectrically conductive path between pad 1016 and bumped terminal 1038and between pad 1016 and filler 1054 not only includes but also requiresrouting line 1036, and an electrically conductive path between pad 1017and bumped terminal 1038 and between pad 1017 and filler 1054 not onlyincludes but also requires routing line 1036. Thus, chips 1010 and 1011are both embedded in encapsulant 1070 and electrically connected tobumped terminal 1038 and filler 1054 by an electrically conductive paththat includes routing line 1036.

Semiconductor chip assembly 1098 includes chips 1010 and 1011, routingline 1036, bumped terminal 1038, filler 1054, plated contact 1064,adhesives 1066 and 1067, connection joints 1068 and 1069, encapsulant1070, insulative base 1076 and plated terminal 1080.

FIGS. 33A-54A, 33B-54B and 33C-54C are cross-sectional, top and bottomviews, respectively, of a method of making a semiconductor chip assemblyin accordance with an eleventh embodiment of the present invention. Inthe eleventh embodiment, the routing line contacts the bumped terminal.For purposes of brevity, any description in the first embodiment isincorporated herein insofar as the same is applicable, and the samedescription need not be repeated. Likewise, elements of the eleventhembodiment similar to those in the first embodiment have correspondingreference numerals indexed at eleven-hundred rather than one-hundred.For instance, chip 1110 corresponds to chip 110, routing line 1136corresponds to routing line 136, etc.

FIGS. 33A, 33B and 33C are cross-sectional, top and bottom views,respectively, of semiconductor chip 1110 which includes opposing majorsurfaces 1112 and 1114. Surface 1112 includes conductive pad 1116 andpassivation layer 1118.

FIGS. 34A, 34B and 34C are cross-sectional, top and bottom views,respectively, of metal base 1120 which includes opposing major surfaces1122 and 1124.

FIGS. 35A, 35B and 35C are cross-sectional, top and bottom views,respectively, of photoresist layers 1126 and 1128 formed on metal base1120. Photoresist layer 1126 contains an opening that selectivelyexposes surface 1122 of metal base 1120, and photoresist layer 1128remains unpatterned.

FIGS. 36A, 36B and 36C are cross-sectional, top and bottom views,respectively, of recess 1130 formed in metal base 1120 by applying a wetchemical etch using photoresist layer 1126 as an etch mask.

FIGS. 37A, 37B and 37C are cross-sectional, top and bottom views,respectively, of bumped terminal 1138 formed on metal base 1120.

Bumped terminal 1138 contacts metal base 1120 in recess 1130 and isdisposed within recess 1130, contours to recess 1130, covers recess 1130in the upward direction but does not fill recess 1130. Bumped terminal1138 is composed of a nickel layer electroplated on metal base 1120, hasa thickness of 10 microns and includes cavity 1146.

Bumped terminal 1138 is formed by an electroplating operation usingphotoresist layers 1126 and 1128 as plating masks. Thus, bumped terminal1138 is formed additively. Initially, a plating bus (not shown) isconnected to metal base 1120, current is applied to the plating bus froman external power source, and the structure is submerged in anelectrolytic nickel plating solution such as Technic Techni Nickel “S”at room temperature. As a result, the nickel layer electroplates on theexposed portion of metal base 1120. The nickel electroplating operationcontinues until the nickel layer has the desired thickness. Thereafter,the structure is removed from the electrolytic nickel plating solutionand rinsed in distilled water to remove contaminants.

FIGS. 38A, 38B and 38C are cross-sectional, top and bottom views,respectively, of filler 1154 formed on bumped terminal 1138.

Filler 1154 contacts and is electrically connected to bumped terminal1138 in cavity 1146, is disposed within cavity 1146, contours to cavity1146, covers cavity 1146 in the upward direction, fills cavity 1146 andis spaced from metal base 1120. Filler 1154 is composed of a copperlayer electroplated on bumped terminal 1138 and has a substantiallyhemispherical shape.

Filler 1154 is formed by an electroplating operation using photoresistlayers 1126 and 1128 as plating masks. Thus, filler 1154 is formedadditively. Initially, a plating bus (not shown) is connected to metalbase 1120, current is applied to the plating bus from an external powersource, and the structure is submerged in an electrolytic copper platingsolution such as Sel-Rex CUBATH M™ at room temperature. As a result, thecopper layer electroplates on the exposed portion of bumped terminal1138. The copper electroplating operation continues until the copperlayer fills cavity 1146. Thereafter, the structure is removed from theelectrolytic copper plating solution and rinsed in distilled water toremove contaminants.

FIGS. 39A, 39B and 39C are cross-sectional, top and bottom views,respectively, of metal base 1120, bumped terminal 1138 and filler 1154after photoresist layers 1126 and 1128 are stripped.

FIGS. 40A, 40B and 40C are cross-sectional, top and bottom views,respectively, of photoresist layers 1132 and 1134 formed on metal base1120. Photoresist layer 1132 is patterned to reshape the openingrelative to photoresist layer 132.

FIGS. 41A, 41B and 41C are cross-sectional, top and bottom views,respectively, of routing line 1136 formed on metal base 1120, bumpedterminal 1138 and filler 1154.

Routing line 1136 contacts and is electrically connected to metal base1120, bumped terminal 1138 and filler 1154 and is disposed upwardlybeyond metal base 1120, bumped terminal 1138 and filler 1154. Inparticular, routing line 1136 contacts metal base 1120 outside theperiphery of bumped terminal 1138, contacts bumped terminal 1138 withinthe periphery of recess 1130 and outside the periphery of cavity 1146,and contacts filler 1154 within the periphery of cavity 1146 outsidecavity 1146. Thus, routing line 1136 extends upwardly beyond metal base1120, bumped terminal 1138 and filler 1154 where routing line 1136contacts metal base 1120, bumped terminal 1138 and filler 1154 and doesnot extend into cavity 1146.

Routing line 1136 consists of elongated routing portion 1142 andincludes distal end 1190 that contacts metal filler 1154 within theperiphery of cavity 1146 and is spaced from bumped terminal 1138. Thus,routing line 1136 overlaps but does not cover metal base 1120, bumpedterminal 1138 or filler 1154 in the upward direction. Furthermore, theenlarged annular portion (corresponding to enlarged annular portion 144)is omitted.

Routing line 1136 is composed of a nickel layer electroplated on metalbase 1120, bumped terminal 1138 and filler 1154 and a copper layerelectroplated on the nickel layer. The nickel layer contacts and issandwiched between metal base 1120 and the copper layer, between bumpedterminal 1138 and the copper layer and between filler 1154 and thecopper layer, and the copper layer contacts the nickel layer and isspaced from metal base 1120, bumped terminal 1138 and filler 1154. Thus,the nickel layer is buried beneath the copper layer, and the copperlayer is exposed. Routing line 1136 has a thickness of 20 microns. Inparticular, the nickel layer has a thickness of 1 micron, and the copperlayer has a thickness of 19 microns. For convenience of illustration,the nickel and copper layers are shown as a single layer.

Routing line 1136 is formed by an electroplating operation usingphotoresist layers 1132 and 1134 as plating masks. Thus, routing line1136 is formed additively. Initially, a plating bus (not shown) isconnected to metal base 1120, current is applied to the plating bus froman external power source, and the structure is submerged in anelectrolytic nickel plating solution such as Technic Techni Nickel “S”at room temperature. As a result, the nickel layer electroplates on theexposed portions of metal base 1120, bumped terminal 1138 and filler1154. The nickel electroplating operation continues until the nickellayer has the desired thickness. Thereafter, the structure is removedfrom the electrolytic nickel plating solution and submerged in anelectrolytic copper plating solution such as Sel-Rex CUBATH M™ at roomtemperature while current is applied to the plating bus to electroplatethe copper layer on the nickel layer. The copper electroplatingoperation continues until the copper layer has the desired thickness.Thereafter, the structure is removed from the electrolytic copperplating solution and rinsed in distilled water to remove contaminants.

FIGS. 42A, 42B and 42C are cross-sectional, top and bottom views,respectively, of metal base 1120, routing line 1136, bumped terminal1138 and filler 1154 after photoresist layers 1132 and 1134 arestripped.

FIGS. 43A, 43B and 43C are cross-sectional, top and bottom views,respectively, of photoresist layers 1160 and 1162 formed on metal base1120.

FIGS. 44A, 44B and 44C are cross-sectional, top and bottom views,respectively, of plated contact 1164 formed on routing line 1136 byelectroplating.

FIGS. 45A, 45B and 45C are cross-sectional, top and bottom views,respectively, of metal base 1120, routing line 1136, bumped terminal1138, filler 1154 and plated contact 1164 after photoresist layers 1160and 1162 are stripped.

FIGS. 46A, 46B and 46C are cross-sectional, top and bottom views,respectively, of adhesive 1166 formed on metal base 1120.

FIGS. 47A, 47B and 47C are cross-sectional, top and bottom views,respectively, of chip 1110 mechanically attached to metal base 1120,routing line 1136, bumped terminal 1138, filler 1154 and plated contact1164 by adhesive 1166.

FIGS. 48A, 48B and 48C are cross-sectional, top and bottom views,respectively, of connection joint 1168 formed on pad 1116 and platedcontact 1164.

FIGS. 49A, 49B and 49C are cross-sectional, top and bottom views,respectively, of encapsulant 1170 formed on chip 1110, routing line1136, bumped terminal 1138, filler 1154, plated contact 1164, adhesive1166 and connection joint 1168. Encapsulant 1170 contacts routing line1136 and filler 1154 within the periphery of cavity 1146 but does notextend into cavity 1146.

FIGS. 50A, 50B and 50C are cross-sectional, top and bottom views,respectively, of the structure after metal base 1120 is removed.

FIGS. 51A, 51B and 51C are cross-sectional, top and bottom views,respectively, of insulative base 1176 formed on routing line 1136,bumped terminal 1138, adhesive 1166 and encapsulant 1170.

FIGS. 52A, 52B and 52C are cross-sectional, top and bottom views,respectively, of the structure after bumped terminal 1138, filler 1154and insulative base 1176 are grinded and laterally aligned with oneanother at lateral surface 1178.

FIGS. 53A, 53B and 53C are cross-sectional, top and bottom views,respectively, of solder terminal 1188 formed on bumped terminal 1138 andfiller 1154.

Solder terminal 1188 is formed in the same manner as solder terminal988. Solder terminal 1188 contacts and is electrically connected tobumped terminal 1138 and filler 1154, is spaced from chip 1110, routingline 1136, plated contact 1164, adhesive 1166, connection joint 1168 andencapsulant 1170, extends downwardly beyond chip 1110, routing line1136, bumped terminal 1138, filler 1154, plated contact 1164, adhesive1166, connection joint 1168, encapsulant 1170 and insulative base 1176and is exposed.

Conductive trace 1182 includes routing line 1136, bumped terminal 1138,filler 1154, plated contact 1164 and solder terminal 1188.

FIGS. 54A, 54B and 54C are cross-sectional, top and bottom views,respectively, of the structure after cutting encapsulant 1170 andinsulative base 1176 with an excise blade to singulate the assembly fromother assemblies.

At this stage, the manufacture of semiconductor chip assembly 1198 thatincludes chip 1110, routing line 1136, bumped terminal 1138, filler1154, plated contact 1164, adhesive 1166, connection joint 1168,encapsulant 1170, insulative base 1176 and solder terminal 1188 can beconsidered complete.

FIGS. 55A, 55B and 55C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with atwelfth embodiment of the present invention. In the twelfth embodiment,the routing line includes a bent corner that slants upwardly. Forpurposes of brevity, any description in the eleventh embodiment isincorporated herein insofar as the same is applicable, and the samedescription need not be repeated. Likewise, elements of the twelfthembodiment similar to those in the eleventh embodiment havecorresponding reference numerals indexed at twelve-hundred rather thaneleven-hundred. For instance, chip 1210 corresponds to chip 1110,routing line 1236 corresponds to routing line 1136, etc.

Filler 1254 fills and extends outside cavity 1246 and extends upwardlybeyond bumped terminal 1238 and cavity 1246 but does not extend upwardlybeyond chip 1210 or routing line 1236. Furthermore, filler 1254 isdisposed within the periphery of cavity 1246, and a majority (but notall) of filler 1254 is disposed within cavity 1246. This is accomplishedby a slight adjustment to the electroplating operation previouslydescribed for filler 1154. In particular, the electroplating operationoccurs for a longer time so that filler 1254 continues to electroplateon bumped terminal 1238 after filler 1254 fills cavity 1246.

Routing line 1236 includes bent corner 1292 that contacts filler 1254and slants upwardly as bent corner 1292 extends laterally into theperiphery of cavity 1246 and extends laterally away from chip 1210.Thus, routing line 1236 is disposed outside cavity 1246 and contactsfiller 1254 within the periphery of cavity 1246 outside cavity 1246, anddistal end 1290 is elevated upwardly and contacts filler 1254 within theperiphery of cavity 1246 outside cavity 1246 and is spaced from bumpedterminal 1238.

Semiconductor chip assembly 1298 includes chip 1210, routing line 1236,bumped terminal 1238, filler 1254, plated contact 1264, adhesive 1266,connection joint 1268, encapsulant 1270, insulative base 1276 and solderterminal 1288.

FIGS. 56A, 56B and 56C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with athirteenth embodiment of the present invention. In the thirteenthembodiment, the routing line includes a bent corner that slantsdownwardly. For purposes of brevity, any description in the eleventhembodiment is incorporated herein insofar as the same is applicable, andthe same description need not be repeated. Likewise, elements of thethirteenth embodiment similar to those in the eleventh embodiment havecorresponding reference numerals indexed at thirteen-hundred rather thaneleven-hundred. For instance, chip 1310 corresponds to chip 1110,routing line 1336 corresponds to routing line 1136, etc.

Filler 1354 is disposed within but does not fill cavity 1346.Furthermore, filler 1354 fills a majority (but not all) of cavity 1346.This is accomplished by a slight adjustment to the electroplatingoperation previously described for filler 1154. In particular, theelectroplating operation occurs for a shorter time so that filler 1354ceases to electroplate on bumped terminal 1338 before filler 1354 fillscavity 1346.

Routing line 1336 includes bent corner 1392 that contacts filler 1354and slants downwardly as bent corner 1392 extends laterally into theperiphery of cavity 1346 and extends laterally away from chip 1310.Thus, routing line 1336 extends into cavity 1346 and contacts filler1354 within cavity 1346, and distal end 1390 is recessed downwardly andcontacts filler 1354 within cavity 1346 and is spaced from bumpedterminal 1338.

Encapsulant 1370 contacts routing line 1336 and filler 1354 withincavity 1346. Furthermore, routing line 1336, filler 1354 and encapsulant1370 fill cavity 1346.

Semiconductor chip assembly 1398 includes chip 1310, routing line 1336,bumped terminal 1338, filler 1354, plated contact 1364, adhesive 1366,connection joint 1368, encapsulant 1370, insulative base 1376 and solderterminal 1388.

FIGS. 57A, 57B and 57C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with afourteenth embodiment of the present invention. In the fourteenthembodiment, the routing line covers the filler. For purposes of brevity,any description in the eleventh embodiment is incorporated hereininsofar as the same is applicable, and the same description need not berepeated. Likewise, elements of the fourteenth embodiment similar tothose in the eleventh embodiment have corresponding reference numeralsindexed at fourteen-hundred rather than eleven-hundred. For instance,chip 1410 corresponds to chip 1110, routing line 1436 corresponds torouting line 1136, etc.

Routing line 1436 is formed with enlarged circular portion 1444 (similarto enlarged annular portion 144 except that it is circular rather thanannular). This is accomplished by a slight adjustment to theelectroplating operation previously described for routing line 1136. Inparticular, the photoresist layer (corresponding to photoresist layer1132) is patterned in the same manner as photoresist layer 132 and hasthe same opening as photoresist layer 132. As a result, routing line1436 covers bumped terminal 1438 and filler 1454 in the upwarddirection, and encapsulant 1470 is spaced from bumped terminal 1438 andfiller 1454.

Semiconductor chip assembly 1498 includes chip 1410, routing line 1436,bumped terminal 1438, filler 1454, plated contact 1464, adhesive 1466,connection joint 1468, encapsulant 1470, insulative base 1476 and solderterminal 1488.

FIGS. 58A, 58B and 58C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with afifteenth embodiment of the present invention. In the fifteenthembodiment, the filler is solder and electrolessly plated metal. Forpurposes of brevity, any description in the eleventh embodiment isincorporated herein insofar as the same is applicable, and the samedescription need not be repeated. Likewise, elements of the fifteenthembodiment similar to those in the eleventh embodiment havecorresponding reference numerals indexed at fifteen-hundred rather thaneleven-hundred. For instance, chip 1510 corresponds to chip 1110,routing line 1536 corresponds to routing line 1136, etc.

Filler 1554 is composed of a solder layer electroplated on bumpedterminal 1538 and a gold layer electrolessly plated on the solder layer.The solder layer contacts and is sandwiched between bumped terminal 1538and the gold layer, and the gold layer contacts the solder layer and isspaced from bumped terminal 1538. For convenience of illustration, thesolder and gold layers are shown as a single layer.

Filler 1554 is formed by an electroplating operation followed by anelectroless plating operation using the photoresist layers(corresponding to photoresist layers 1126 and 1128) as plating masks.Thus, filler 1554 is formed additively. Initially, a plating bus (notshown) is connected to the metal base (corresponding to metal base1120), current is applied to the plating bus from an external powersource, and the structure is submerged in an electrolytic solder platingsolution such as Technic Solder NF 72 BC at room temperature. As aresult, the solder layer electroplates on the exposed portion of bumpedterminal 1538. Thereafter, the structure is removed from theelectrolytic solder plating solution, disconnected from the plating busand submerged in an electroless gold plating solution such as isMacDermid PLANAR™ at 70° C. Filler 1554 includes an exposed solder layerand therefore is catalytic to electroless gold. As a result, the golddeposits on the solder layer. The gold electroless plating operationcontinues until the gold layer is 0.5 microns thick. Thereafter, thestructure is removed from the electroless gold plating solution andrinsed in distilled water to remove contaminants.

Thereafter, the photoresist layers (corresponding to photoresist layers1126 and 1128) are stripped, the photoresist layers (corresponding tophotoresist layers 1132 and 1134) are formed and routing line 1536 iselectroplated on the metal base, bumped terminal 1538 and filler 1554.The gold layer of filler 1554 increases the stability of filler 1554during the electroplating operation that forms routing line 1536.

Semiconductor chip assembly 1598 includes chip 1510, routing line 1536,bumped terminal 1538, filler 1554, plated contact 1564, adhesive 1566,connection joint 1568, encapsulant 1570, insulative base 1576 and solderterminal 1588.

FIGS. 59A, 59B and 59C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with asixteenth embodiment of the present invention. In the sixteenthembodiment, the filler is solder. For purposes of brevity, anydescription in the eleventh embodiment is incorporated herein insofar asthe same is applicable, and the same description need not be repeated.Likewise, elements of the sixteenth embodiment similar to those in theeleventh embodiment have corresponding reference numerals indexed atsixteen-hundred rather than eleven-hundred. For instance, chip 1610corresponds to chip 1110, routing line 1636 corresponds to routing line1136, etc.

Filler 1654 is formed by depositing solder paste into cavity 1646 afterstripping the photoresist layer (corresponding to photoresist layer1126) that provides the etch mask for the recess (corresponding torecess 1130) and the plating mask for bumped terminal 1638. Thereafter,the solder paste is heated and reflowed to form hardened solder, andthen routing line 1636 is formed.

Semiconductor chip assembly 1698 includes chip 1610, routing line 1636,bumped terminal 1638, filler 1654, plated contact 1664, adhesive 1666,connection joint 1668, encapsulant 1670, insulative base 1676 and solderterminal 1688.

FIGS. 60A, 60B and 60C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with aseventeenth embodiment of the present invention. In the seventeenthembodiment, the filler is conductive adhesive. For purposes of brevity,any description in the eleventh embodiment is incorporated hereininsofar as the same is applicable, and the same description need not berepeated. Likewise, elements of the seventeenth embodiment similar tothose in the eleventh embodiment have corresponding reference numeralsindexed at seventeen-hundred rather than eleven-hundred. For instance,chip 1710 corresponds to chip 1110, routing line 1736 corresponds torouting line 1136, etc.

Filler 1754 is formed by depositing conductive adhesive into cavity 1746after stripping the photoresist layer (corresponding to photoresistlayer 1126) that provides the etch mask for the recess (corresponding torecess 1130) and the plating mask for bumped terminal 1738. Thereafter,the conductive adhesive is heated and cured to form hardened conductiveadhesive, and then routing line 1736 is formed.

Semiconductor chip assembly 1798 includes chip 1710, routing line 1736,bumped terminal 1738, filler 1754, plated contact 1764, adhesive 1766,connection joint 1768, encapsulant 1770, insulative base 1776 and solderterminal 1788.

FIGS. 61A, 61B and 61C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with aneighteenth embodiment of the present invention. In the eighteenthembodiment, the assembly includes a solder mask. For purposes ofbrevity, any description in the eleventh embodiment is incorporatedherein insofar as the same is applicable, and the same description neednot be repeated. Likewise, elements of the eighteenth embodiment similarto those in the eleventh embodiment have corresponding referencenumerals indexed at eighteen-hundred rather than eleven-hundred. Forinstance, chip 1810 corresponds to chip 1110, routing line 1836corresponds to routing line 1136, etc.

After plated contact 1864 is formed, solder mask 1894 is formed on themetal base (corresponding to metal base 1120), routing line 1836, bumpedterminal 1838 and filler 1854. Solder mask 1894 is initially aphotoimageable liquid resin that is dispensed on the metal base, routingline 1836, bumped terminal 1838, filler 1854 and plated contact 1864.Thereafter, solder mask 1894 is patterned by selectively applying lightthrough a reticle (not shown), applying a developer solution to removethe solder mask portions rendered soluble by the light, and then hardbaking, as is conventional. As a result, solder mask 1894 containsopening 1895 that is vertically aligned with and exposes plated contact1864.

Adhesive 1866 contacts and is sandwiched between chip 1810 and soldermask 1894, connection joint 1868 extends into opening 1895, andencapsulant 1870 contacts solder mask 1894 and is spaced from bumpedterminal 1838 and filler 1854.

Semiconductor chip assembly 1898 includes chip 1810, routing line 1836,bumped terminal 1838, filler 1854, plated contact 1864, adhesive 1866,connection joint 1868, encapsulant 1870, insulative base 1876, solderterminal 1888 and solder mask 1894.

FIGS. 62A, 62B and 62C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with anineteenth embodiment of the present invention. In the nineteenthembodiment, the solder terminal is omitted. For purposes of brevity, anydescription in the eleventh embodiment is incorporated herein insofar asthe same is applicable, and the same description need not be repeated.Likewise, elements of the nineteenth embodiment similar to those in theeleventh embodiment have corresponding reference numerals indexed atnineteen-hundred rather than eleven-hundred. For instance, chip 1910corresponds to chip 1110, routing line 1936 corresponds to routing line1136, etc.

The solder terminal (corresponding to solder terminal 1188) is omitted.Thus, bumped terminal 1938 and filler 1954 are exposed at lateralsurface 1978.

Semiconductor chip assembly 1998 includes chip 1910, routing line 1936,bumped terminal 1938, filler 1954, plated contact 1964, adhesive 1966,connection joint 1968, encapsulant 1970 and insulative base 1976.

FIGS. 63A, 63B and 63C are cross-sectional, top and bottom views,respectively, of a semiconductor chip assembly in accordance with atwentieth embodiment of the present invention. In the twentiethembodiment, the bumped terminal is removed. For purposes of brevity, anydescription in the eleventh embodiment is incorporated herein insofar asthe same is applicable, and the same description need not be repeated.Likewise, elements of the twentieth embodiment similar to those in theeleventh embodiment have corresponding reference numerals indexed attwo-thousand rather than eleven-hundred. For instance, chip 2010corresponds to chip 1110, routing line 2036 corresponds to routing line1136, etc.

After the metal base (corresponding to metal base 1120) is removed, thebumped terminal (corresponding to bumped terminal 1138) is removed byapplying a blanket back-side wet chemical etch. For instance, the bottomspray nozzle can spray the wet chemical etch on the bumped terminalwhile the top spray nozzle is deactivated, or the structure can bedipped in the wet chemical etch since encapsulant 2070 providesfront-side protection.

The wet chemical etch is highly selective of nickel with respect topolyimide and the molding compound, and therefore, highly selective ofthe bumped terminal with respect to adhesive 2066 and encapsulant 2070.The wet chemical etch also removes the exposed portion of the nickellayer of routing line 2036 (that extends laterally beyond filler 2054and downwardly beyond the copper layer of routing line 2036).

Since the bumped terminal is thin relative to routing line 2036 andfiller 2054, and the structure is removed from the wet chemical etchsoon after the bumped terminal is stripped, it is not critical that thewet chemical etch be highly selective of nickel with respect to copper.In fact, the wet chemical etch is also selective of copper. As a result,the wet chemical etch also removes a slight amount of the exposed coppersurfaces of routing line 2036 and filler 2054. However, the wet chemicaletch is not applied long enough to appreciably affect routing line 2036or filler 2054. Furthermore, chip 2010, plated contact 2064 andconnection joint 2068 are not exposed to the wet chemical etch.

The wet chemical etch removes the bumped terminal. As a result, the wetchemical etch exposes filler 2054 without exposing chip 2010, platedcontact 2064 or connection joint 2068. The wet chemical etch alsoconverts routing line 2036 from a flat, planar lead to an essentiallyflat, planar lead due to the slight recess (not shown) previouslyoccupied by a portion of the nickel layer that extended laterally beyondfiller 2054 and a lower portion of a portion of the copper layer thatextended laterally beyond filler 2054.

A suitable wet chemical etch can be provided by a solution containing adilute mixture of nitric and hydrochloric acid. The optimal etch timefor removing the bumped terminal without excessively exposing routingline 2036 and filler 2054 to the wet chemical etch can be establishedthrough trial and error.

Insulative base 2076 is formed after removing the bumped terminal.Insulative base 2076 includes aperture 2096 that is similar to thecavity (corresponding to cavity 1146) in the bumped terminal. As aresult, filler 2054 contacts insulative base 2076 in aperture 2096. Atthis stage, aperture 2096 extends into but not through insulative base2076, is not covered by insulative base 2076 in the upward direction andis covered by insulative base 2076 in the downward direction. In otherwords, aperture 2096 extends through insulative base 2076 in the upwarddirection but not the downward direction.

Thereafter, the grinding operation is performed. Initially, the diamondsand wheel grinds only insulative base 2076. As the grinding continues,insulative base 2076 becomes thinner as the grinded surface migratesupwardly. Eventually the diamond sand wheel contacts filler 2054, and asa result, begins to grind filler 2054 as well. As the grindingcontinues, filler 2054 and insulative base 2076 become thinner as theirgrinded surfaces migrate upwardly. The grinding continues until filler2054 and insulative base 2076 have the desired thickness, and then haltsbefore it reaches chip 2010, routing line 2036, plated contact 2064,adhesive 2066, connection joint 2068 or encapsulant 2070. Thereafter,the structure is rinsed in distilled water to remove contaminants.

The grinding exposes filler 2054 in aperture 2096 and causes aperture2096 to extend through insulative base 2076 in the downward direction.In addition, filler 2054, insulative base 2076 and aperture 2096 arelaterally aligned with one another at lateral surface 2078. Thus,lateral surface 2078 is an exposed planarized horizontal surface thatfaces downwardly and includes filler 2054, insulative base 2076 andaperture 2096. Furthermore, filler 2054 forms a circle at lateralsurface 2078, and insulative base 2076 surrounds and is adjacent tofiller 2054 at lateral surface 2078.

Semiconductor chip assembly 2698 includes chip 2010, routing line 2036,filler 2054, plated contact 2064, adhesive 2066, connection joint 2068,encapsulant 2070, insulative base 2076 and solder terminal 2088.

The semiconductor chip assemblies described above are merely exemplary.Numerous other embodiments are contemplated. For instance, the platedcontact, plated terminal, solder terminal and insulative base can beomitted. In addition, the embodiments described above can generally becombined with one another. For instance, the plated terminal in thefirst embodiment (and the second to eighth and tenth embodiments) can beused in the eleventh to eighteenth and twentieth embodiments but not thenineteenth embodiment since the contact terminal is omitted. Likewise,the flip-chip in the second embodiment and the plated connection jointsin the third and fourth embodiments can be used in the other embodimentswith wire bond connection joints except for the multi-chip assembly inthe tenth embodiment since the chips are not inverted. Likewise, thesolder filler in the fifth embodiment can be used in the otherembodiments except for the fifteenth to seventeenth embodiments.Likewise, the filler laterally aligned with the encapsulant in the sixthembodiment can be used in the first to fifth and eighth to tenthembodiments. Likewise, the filler covered by the adhesive in the seventhembodiment can be used in the other embodiments except for the sixthembodiment. Likewise, the recessed insulative base in the eighthembodiment can be used in the other embodiments. Likewise, the platedmetal and solder terminal in the ninth embodiment can be used in theother embodiments except for the nineteenth embodiment. Likewise, themulti-chip assembly in the tenth embodiment can be used in the otherembodiments except for the second to fourth embodiments since the chipsare inverted. Likewise, the solder terminal in the eleventh embodiment(and the twelfth to eighteenth and twentieth embodiments) can be used inthe first to eighth and tenth embodiments. Likewise, the routing lineswith bent corners and the fillers in the twelfth and thirteenthembodiments can be used in the fourteenth to twentieth embodiments.Likewise, the routing line that covers the filler in the fourteenthembodiment can be used in the fifteenth to twentieth embodiments.Likewise, the plated metal and solder filler in the fifteenth embodimentcan be used in the twelfth to fourteenth and eighteenth to twentiethembodiments. Likewise, the solder filler in the sixteenth embodiment andthe conductive adhesive filler in the seventeenth embodiment can be usedin the first to fourth, sixth to fourteenth and eighteenth to twentiethembodiments. Likewise, the solder mask in the eighteenth embodiment canbe used in the other embodiments. Likewise, the omitted contact terminalin the nineteenth embodiment can be used in the first to eighth, tenthto eighteenth and twentieth embodiments, and the removed bumped terminalin the twentieth embodiment can be used in the twelfth to nineteenthembodiments.

The embodiments described above can be mixed-and-matched with oneanother and with other embodiments depending on design and reliabilityconsiderations. For instance, the filler covered by the adhesive in theseventh embodiment can be combined with the routing line and the fillerin the thirteenth embodiment such that the bumped terminal, the fillerand the cavity are disposed within the periphery of the chip, therouting line contacts the filler within the cavity, the adhesivecontacts the routing line and the filler within the cavity, and therouting line, the filler and the adhesive fill the cavity.

The metal base need not necessarily be removed. For instance, a portionof the metal base that extends within the periphery of the chip and isspaced from the routing line and the bumped terminal can remain intactand provide a heat sink.

The routing line can be various conductive metals including copper,gold, nickel, silver, palladium, tin, combinations thereof, and alloysthereof. The preferred composition of the routing line will depend onthe nature of the connection joint as well as design and reliabilityfactors. Furthermore, those skilled in the art will understand that inthe context of a semiconductor chip assembly, a copper material istypically a copper alloy that is mostly copper but not pure elementalcopper, such copper-zirconium (99.9% copper),copper-silver-phosphorus-magnesium (99.7% copper), orcopper-tin-iron-phosphorus (99.7% copper). Likewise, the routing linecan fan-in as well as fan-out.

The routing line can be formed on the metal base (or the metal base, thebumped terminal and the filler) by numerous deposition techniquesincluding electroplating and electroless plating. In addition, therouting line can be deposited-on the metal base (or the metal base, thebumped terminal and the filler) as a single layer or multiple layers.For instance, the routing line can be a 10 micron layer of gold, oralternatively, a 9.5 micron layer of nickel electroplated on a 0.5micron layer of gold electroplated on a copper base to reduce costs, oralternatively, a 9 micron layer of nickel electroplated on a 0.5 micronlayer of gold electroplated on a 0.5 micron layer of tin electroplatedon a copper base to reduce costs and avoid gold-copper alloys that maybe difficult to remove when the copper base is etched. As anotherexample, the routing line can consist of a non-copper layerelectroplated on a copper base and a copper layer electroplated on thenon-copper layer. Suitable non-copper layers include nickel, gold,palladium and silver. After the routing line is formed, a wet chemicaletch can be applied that is highly selective of copper with respect tothe non-copper layer to etch the copper base and expose the routing linewithout removing the copper or non-copper layers. The non-copper layerprovides an etch stop that prevents the wet chemical etch from removingthe copper layer. Furthermore, it is understood that in the context ofthe present invention, the routing line and the metal base are differentmetals (or metallic materials) even if a multi-layer routing lineincludes a single layer that is similar to the metal base (such as theexample described above) or a single layer of a multi-layer metal base.

The routing line can also be formed by etching a metal layer attached tothe metal base. For instance, a photoresist layer can be formed on themetal layer, the metal layer can be etched using the photoresist layeras an etch mask, and then the photoresist layer can be stripped.Alternatively, a photoresist layer can be formed on the metal layer, aplated metal can be selectively electroplated on the metal layer usingthe photoresist layer as a plating mask, the photoresist layer can bestripped, and then the metal layer can be etched using the plated metalas an etch mask. In this manner, the routing line can be formedsemi-additively and include unetched portions of the metal layer and theplated metal. Likewise, the routing line can be formed subtractivelyfrom the metal layer, regardless of whether the plated metal etch maskremains attached to the routing line.

The routing line can be spot plated near the pad to make it compatiblewith receiving the connection joint. For instance, a copper routing linecan be spot plated with nickel and then silver to make it compatiblewith a gold ball bond connection joint and avoid the formation ofbrittle silver-copper intermetallic compounds. Likewise, the bumpedterminal can be spot plated in the cavity to make it compatible withreceiving the filler. For instance, a copper bumped terminal can be spotplated in the cavity with nickel and then gold to facilitate solderreflow of a solder filler in the cavity.

The bumped terminal can be various conductive metals including copper,gold, nickel, silver, palladium, tin, combinations thereof, and alloysthereof. The preferred composition of the bumped terminal will depend onthe nature of the filler as well as design and reliability factors. Thebumped terminal can be deposited on the metal base and into the recessby numerous deposition techniques including electroplating andelectroless plating. The bumped terminal can be formed in the samemanner as and simultaneously with the routing line, or alternatively, ina different manner than and before the routing line.

The filler can be various conductive metals including copper, gold,nickel, silver, palladium, tin, solder, combinations thereof, and alloysthereof, and can be deposited on the bumped terminal and into the cavityby a wide variety of processes including electroplating, electrolessplating, evaporating, sputtering, solder reflowing, dispensing andwelding.

The filler can be solder deposited on the bumped terminal and into thecavity by plating or printing or placement techniques. The solder can beelectroplated on the bumped terminal and into the cavity, oralternatively, solder paste or a solder ball can be deposited on thebumped terminal and into the cavity and then heated and reflowed.

The filler can be a metal particle deposited on the bumped terminal andinto the cavity, or alternatively, a conductive bond deposited on thebumped terminal and into the cavity and a metal particle deposited onthe conductive bond and into the cavity. Further details regarding afiller provided by a metal particle attached to a bumped terminal byreflowing, solidifying or hardening the metal particle or a conductivebond are disclosed in U.S. application Ser. No. 10/922,280 filed Aug.19, 2004 by Charles W. C. Lin et al. entitled “Semiconductor ChipAssembly with Embedded Metal Particle” which is incorporated byreference.

The filler can be conductive adhesive that includes (1) a polymer binder(or matrix) and a filler metal powder, or (2) intrinsic conductivepolymer. Suitable polymer binders include epoxy, polyimide and silicone.Suitable filler metal powders include silver, copper, nickel andgraphite. Isotropic conductive adhesives in which the electricalconductivity is identical along the three coordinate axes are generallypreferred. The conductive adhesive can be deposited on the bumpedterminal and into the cavity by depositing a non-solidified conductiveadhesive on the bumped terminal into the cavity and then applying energyto cure and harden the conductive adhesive. Suitable depositionprocesses include screen printing and stencil printing. Heat can besupplied by a convection oven, although other energy sources such asmicrowaves and UV light can be used.

The bumped terminal and the filler can be uncovered in the upwarddirection by the encapsulant, the insulative base or any otherinsulative material of the assembly. For instance, the filler can beexposed in the upward direction and the bumped terminal can be unexposedin the upward direction, or alternatively, the bumped terminal and thefiller can be unexposed in the upward direction and a contact terminal(such as the plated terminal or the solder terminal) that contacts thefiller and overlaps the bumped terminal and the filler can be exposed inthe upward direction, or alternatively, the bumped terminal and thefiller can be covered in the upward direction by an insulative materialexternal to the assembly such as another semiconductor chip assembly ina stacked arrangement. In every case, the bumped terminal and the fillerare not covered in the upward direction by the encapsulant, theinsulative base or any other insulative material of the assembly.

The bumped terminal and the filler can be uncovered in the downwarddirection by the encapsulant, the insulative base or any otherinsulative material of the assembly. For instance, the bumped terminaland the filler can be exposed in the downward direction, oralternatively, the bumped terminal and the filler can be unexposed inthe downward direction and a contact terminal (such as the platedterminal or the solder terminal) that contacts and is overlapped by thebumped terminal and the filler can be exposed in the downward direction,or alternatively, the bumped terminal and the filler can be covered inthe downward direction by an insulative material external to theassembly such as another semiconductor chip assembly in a stackedarrangement. In every case, the bumped terminal and the filler are notcovered in the downward direction by the encapsulant, the insulativebase or any other insulative material of the assembly.

The conductive trace can function as a signal, power or ground layerdepending on the purpose of the associated chip pad.

The pad can have numerous shapes including a flat rectangular shape anda bumped shape. If desired, the pad can be treated to accommodate theconnection joint.

Numerous adhesives can be applied to mechanically attach the chip to themetal base. For instance, the adhesive can be applied as a paste, alaminated layer, or a liquid applied by screen-printing, spin-on, orspray-on. The adhesive can be a single layer that is applied to themetal base or a solder mask and then contacted to the chip or a singlelayer that is applied to the chip and then contacted to the metal baseor a solder mask. Similarly, the adhesive can be multiple layers with afirst layer applied to the metal base or a solder mask, a second layerapplied to the chip and then the layers contacted to one another.Thermosetting adhesive liquids and pastes such as epoxies are generallysuitable. Likewise, thermoplastic adhesives such as an insulativethermoplastic polyimide film with a glass transition temperature (Tg) of400° C. are also generally suitable. Silicone adhesives are alsogenerally suitable.

The encapsulant can be deposited using a wide variety of techniquesincluding printing and transfer molding. For instance, the encapsulantcan be printed on the chip and the filler as an epoxy paste and thencured or hardened to form a solid adherent protective layer. Theencapsulant can be any of the adhesives mentioned above. Moreover, theencapsulant need not necessarily contact the chip or the filler. Forinstance, a glob-top coating can be deposited on the chip afterattaching the chip to the filler, and then the encapsulant can be formedon the glob-top coating. Likewise, a coating (such as flux or solder)can be deposited on the filler, and then the encapsulant can be formedon the coating.

The encapsulant can have its upper portion removed using a wide varietyof techniques including grinding (including mechanical polishing andchemical-mechanical polishing), blanket laser ablation and blanketplasma etching. Likewise, the encapsulant can have a selected portionabove the filler removed using a wide variety of techniques includingselective laser ablation, selective plasma etching and photolithography.

The encapsulant can be laterally aligned with the filler along aupwardly facing lateral surface that extends upwardly beyond the routingline and the bumped terminal by grinding the encapsulant withoutgrinding the bumped terminal, the routing line or the filler, thengrinding the encapsulant and the filler without grinding the routingline or the bumped terminal, and then discontinuing the grinding beforereaching the routing line or the bumped terminal.

The insulative base may be rigid or flexible, and can be variousdielectric films or prepregs formed from numerous organic or inorganicinsulators such as tape (polyimide), epoxy, silicone, glass, aramid andceramic. Organic insulators are preferred for low cost, high dielectricapplications, whereas inorganic insulators are preferred when highthermal dissipation and a matched thermal coefficient of expansion areimportant. For instance, the insulative base can initially be an epoxypaste that includes an epoxy resin, a curing agent, an accelerator and afiller, that is subsequently cured or hardened to form a solid adherentinsulative layer. The filler can be an inert material such as silica(powdered fused quartz) that improves thermal conductivity, thermalshock resistance and thermal coefficient of expansion matching. Organicfiber reinforcement may also be used in resins such as epoxy, cyanateester, polyimide, PTFE and combinations thereof. Fibers that may be usedinclude aramid, polyester, polyamide, poly-ether-ether-ketone,polyimide, polyetherimide and polysulfone. The fiber reinforcement canbe woven fabric, woven glass, random microfiber glass, woven quartz,woven, aramid, non-woven fabric, non-woven aramid fiber or paper.Commercially available dielectric materials such as SPEEDBOARD C prepregby W.L. Gore & Associates of Eau Claire, Wis. are suitable.

The insulative base can be deposited in numerous manners, includingprinting and transfer molding. Furthermore, the insulative base can beformed before or after attaching the chip to the routing line, before orafter forming the encapsulant and before or after grinding theencapsulant. For instance, the metal base can be removed and theinsulative base can be formed after forming the encapsulant and beforegrinding the encapsulant, or alternatively, after grinding theencapsulant. Likewise, the insulative base can be grinded before orafter attaching the chip to the routing line, before or after formingthe encapsulant and before or after grinding the encapsulant. Forinstance, the insulative base can grinded after forming the encapsulantand before grinding the encapsulant, or alternatively, after grindingthe encapsulant.

The insulative base can have its lower portion removed using a widevariety of techniques including grinding (including mechanical polishingand chemical-mechanical polishing), blanket laser ablation and blanketplasma etching. Likewise, the insulative base can have a selectedportion below the bumped terminal and the filler removed using a widevariety of techniques including selective laser ablation, selectiveplasma etching and photolithography.

The insulative base can be laterally aligned with the bumped terminaland the filler along a downwardly facing lateral surface that extendsdownwardly beyond the routing line by grinding the insulative basewithout grinding the bumped terminal or the filler, then grinding theinsulative base and the bumped terminal without grinding the filler,then grinding the insulative base, the bumped terminal and the filler,and then discontinuing the grinding before reaching the routing line.

The connection joint can be formed from a wide variety of materialsincluding copper, gold, nickel, palladium, tin, alloys thereof, andcombinations thereof, can be formed by a wide variety of processesincluding electroplating, electroless plating, ball bonding, wirebonding, stud bumping, solder reflowing, conductive adhesive curing, andwelding, and can have a wide variety of shapes and sizes. The shape andcomposition of the connection joint depends on the composition of therouting line as well as design and reliability considerations. Furtherdetails regarding an electroplated connection joint are disclosed inU.S. application Ser. No. 09/865,367 filed May 24, 2001 by Charles W. C.Lin entitled “Semiconductor Chip Assembly with SimultaneouslyElectroplated Contact Terminal and Connection Joint” which isincorporated by reference. Further details regarding an electrolesslyplated connection joint are disclosed in U.S. application Ser. No.09/864,555 filed May 24, 2001 by Charles W. C. Lin entitled“Semiconductor Chip Assembly with Simultaneously Electrolessly PlatedContact Terminal and Connection Joint” which is incorporated byreference. Further details regarding a ball bond connection joint aredisclosed in U.S. application Ser. No. 09/864,773 filed May 24, 2001 byCharles W. C. Lin entitled “Semiconductor Chip Assembly with Ball BondConnection Joint” which is incorporated by reference. Further detailsregarding a solder or conductive adhesive connection joint are disclosedin U.S. application Ser. No. 09/927,216 filed Aug. 10, 2001 by CharlesW. C. Lin entitled “Semiconductor Chip Assembly with Hardened ConnectionJoint” which is incorporated by reference. Further details regarding awelded connection joint are disclosed in U.S. application Ser. No.10/302,642 filed Nov. 23, 2002 by Cheng-Lien Chiang et al. entitled“Method of Connecting a Conductive Trace to a Semiconductor Chip UsingPlasma Undercut Etching” which is incorporated by reference.

After the connection joint is formed, if a plating bus exists then it isdisconnected from the conductive trace. The plating bus can bedisconnected by mechanical sawing, laser cutting, chemical etching, andcombinations thereof. If the plating bus is disposed about the peripheryof the assembly but is not integral to the assembly, then the platingbus can be disconnected when the assembly is singulated from otherassemblies. However, if the plating bus is integral to the assembly, orsingulation has already occurred, then a photolithography step can beadded to selectively cut related circuitry on the assembly that isdedicated to the plating bus since this circuitry would otherwise shortthe conductive traces together. Furthermore, the plating bus can bedisconnected by etching the metal base.

A soldering material or solder ball can be deposited on the conductivetrace by plating or printing or placement techniques if required for thenext level assembly. However, the next level assembly may not requirethat the semiconductor chip assembly contain solder. For instance, inland grid array (LGA) packages, the soldering material is normallyprovided by the panel rather than the contact terminals on thesemiconductor chip assembly.

Various cleaning steps, such as a brief oxygen plasma cleaning step, ora brief wet chemical cleaning step using a solution containing potassiumpermanganate, can be applied to the structure at various stages, such asimmediately before forming the connection joint to clean the conductivetrace and the pad.

It is understood that, in the context of the present invention, any chipembedded in the encapsulant is electrically connected to the bumpedterminal and the filler by an electrically conductive path that includesthe routing line means that the routing line is in an electricallyconductive path between the bumped terminal and any chip embedded in theencapsulant and between the filler and any chip embedded in theencapsulant. This is true regardless of whether a single chip isembedded in the encapsulant (in which case the chip is electricallyconnected to the bumped terminal and the filler by an electricallyconductive path that includes the routing line) or multiple chips areembedded in the encapsulant (in which case each of the chips iselectrically connected to the bumped terminal and the filler by anelectrically conductive path that includes the routing line). This isalso true regardless of whether the electrically conductive pathincludes or requires a connection joint and/or a plated contact betweenthe routing line and the chip. This is also true regardless of whetherthe electrically conductive path includes or requires a passivecomponent such as a capacitor or a resistor. This is also trueregardless of whether multiple chips are electrically connected to therouting line by multiple connection joints, and the multiple connectionjoints are electrically connected to one another only by the routingline. This is also true regardless of whether multiple chips areelectrically connected to the bumped terminal and the filler bydifferent electrically conductive paths (such as the multiple connectionjoint example described above) as long as each of the electricallyconductive paths includes the routing line.

The “upward” and “downward” vertical directions do not depend on theorientation of the assembly, as will be readily apparent to thoseskilled in the art. For instance, the encapsulant extends verticallybeyond the routing line in the “upward” direction, the bumped terminalextends vertically beyond the routing line in the “downward” directionand the insulative base extends vertically beyond the encapsulant in the“downward” direction, regardless of whether the assembly is invertedand/or mounted on a printed circuit board. Likewise, the routing lineextends “laterally” beyond the bumped terminal and the filler regardlessof whether the assembly is inverted, rotated or slanted. Thus, the“upward” and “downward” directions are opposite one another andorthogonal to the “lateral” direction, and the “laterally aligned”surfaces are coplanar with one another in a lateral plane orthogonal tothe upward and downward directions. Moreover, the chip is shown abovethe routing line, the bumped terminal and the insulative base, and theencapsulant is shown above the chip, the routing line, the bumpedterminal, the filler and the insulative base with a single orientationthroughout the drawings for ease of comparison between the figures,although the assembly and its components may be inverted at variousmanufacturing stages.

The working format for the semiconductor chip assembly can be a singleassembly or multiple assemblies based on the manufacturing design. Forinstance, a single assembly that includes a single chip can bemanufactured individually. Alternatively, numerous assemblies can besimultaneously batch manufactured on a single metal base with a singleencapsulant and a single insulative base then separated from oneanother.

For example, recesses for multiple assemblies can be simultaneouslyetched in the metal base, then routing lines and bumped terminals forthe multiple assemblies can be simultaneously electroplated on the metalbase with the bumped terminals electroplated in the correspondingrecesses, then fillers can be simultaneously electroplated on thecorresponding bumped terminals, then plated contacts can besimultaneously electroplated on the corresponding routing lines, thenseparate spaced adhesives for the respective assemblies can beselectively disposed on the metal base, then the chips can be disposedon the corresponding adhesives, then the adhesives can be simultaneouslyfully cured, then the connection joints can be formed on thecorresponding plated contacts and pads, then the encapsulant can beformed, then the metal base can be etched and removed, then theinsulative base can be formed, then the insulative base, the bumpedterminals and the fillers can be grinded, then the plated terminals canbe simultaneously electrolessly plated on the corresponding bumpedterminals and fillers, and then the encapsulant and the insulative basecan be cut, thereby separating the individual single chip-substrateassemblies.

As another example, recesses for multiple assemblies can besimultaneously etched in the metal base, then bumped terminals for themultiple assemblies can be simultaneously electroplated on the metalbase in the corresponding recesses, then fillers can be simultaneouslyelectroplated on the corresponding bumped terminals, then routing linescan be simultaneously electroplated on the metal base and thecorresponding bumped terminals and fillers, then plated contacts can besimultaneously electroplated on the corresponding routing lines, thenseparate spaced adhesives for the respective assemblies can beselectively disposed on the metal base, then the chips can be disposedon the corresponding adhesives, then the adhesives can be simultaneouslyfully cured, then the connection joints can be formed on thecorresponding plated contacts and pads, then the encapsulant can beformed, then the metal base can be etched and removed, then theinsulative base can be formed, then the insulative base, the bumpedterminals and the fillers can be grinded, then the solder terminals canbe deposited on the corresponding bumped terminals and fillers, then thesolder terminals can be simultaneously reflowed, and then theencapsulant and the insulative base can be cut, thereby separating theindividual single chip-substrate assemblies.

The semiconductor chip assembly can have a wide variety of packagingformats as required by the next level assembly. For instance, theconductive traces can be configured so that the assembly is a grid arraysuch as a ball grid array (BGA), column grid array (CGA), land gridarray (LGA) or pin grid array (PGA).

The semiconductor chip assembly can be a first-level package that is asingle-chip package (such as the first to ninth and eleventh totwentieth embodiments) or a multi-chip package (such as the tenthembodiment). Furthermore, a multi-chip first-level package can includechips that are stacked and vertically aligned with one another or arecoplanar and laterally aligned with one another.

Advantageously, the semiconductor chip assembly of the present inventionis reliable and inexpensive. The encapsulant and the insulative base canprotect the chip from handling damage, provide a known dielectricbarrier for the conductive trace and protect the assembly fromcontaminants and unwanted solder reflow during the next level assembly.The encapsulant can provide mechanical support for the conductive traceas the metal base is etched and removed. In addition, the filler cancontact the bumped terminal in the cavity, thereby improvingreliability. The mode of the connection can shift from the initialmechanical coupling to metallurgical coupling to assure sufficientmetallurgical bond strength. Furthermore, the conductive trace can bemechanically and metallurgically coupled to the chip without wirebonding, TAB, solder or conductive adhesive, although the process isflexible enough to accommodate these techniques if desired. The processis highly versatile and permits a wide variety of mature connectionjoint technologies to be used in a unique and improved manner. As aresult, the assembly of the present invention significantly enhancesthroughput, yield and performance characteristics compared toconventional packaging techniques. Moreover, the assembly of the presentinvention is well-suited for use with materials compatible with copperchip requirements.

Various changes and modifications to the presently preferred embodimentsdescribed herein will be apparent to those skilled in the art. Forinstance, the materials, dimensions and shapes described above aremerely exemplary. Such changes and modifications may be made withoutdeparting from the spirit and scope of the present invention as definedin the appended claims.

1. A semiconductor chip assembly, comprising: a semiconductor chip thatincludes first and second opposing surfaces, wherein the first surfaceof the chip includes a conductive pad; a conductive trace that includesa routing line, a bumped terminal and a filler, wherein the bumpedterminal includes a cavity; a connection joint that electricallyconnects the routing line and the pad; and an encapsulant that includesfirst and second opposing surfaces, wherein the first surface ofencapsulant faces in a first direction, the second surface of theencapsulant faces in a second direction opposite the first direction,the chip is embedded in the encapsulant, the routing line contacts thebumped terminal, contacts the filler within a periphery of the cavity,extends laterally beyond the bumped terminal and the filler, extendsvertically beyond the bumped terminal and the filler in the firstdirection where the routing line contacts the bumped terminal and thefiller and extends vertically beyond the chip in the second direction,the bumped terminal extends vertically beyond the routing line in thesecond direction and does not extend vertically beyond the routing linein the first direction, the cavity extends through the bumped terminalin the first and second directions, the filler contacts the bumpedterminal in the cavity and extends vertically beyond the routing line inthe second direction, the bumped terminal, the cavity and the filler arelaterally aligned with one another at a lateral surface that faces inthe second direction and are not covered in the second direction by theencapsulant or any other insulative material of the assembly, the bumpedterminal surrounds the filler and only the filler at the lateralsurface, is adjacent to the filler at the lateral surface and has asmaller surface area than the filler at the lateral surface, and theassembly is devoid of a printed circuit board.
 2. The assembly of claim1, wherein the first surface of the chip faces in the first direction,and the second surface of the chip faces in the second direction.
 3. Theassembly of claim 1, wherein the first surface of the chip faces in thesecond direction, and the second surface of the chip faces in the firstdirection.
 4. The assembly of claim 1, wherein the chip is the only chipembedded in the encapsulant.
 5. The assembly of claim 1, wherein thechip and another chip are embedded in the encapsulant.
 6. The assemblyof claim 1, wherein the chip extends vertically beyond the routing line,the bumped terminal and the filler in the first direction.
 7. Theassembly of claim 1, wherein the chip extends vertically beyond theconductive trace in the first direction.
 8. The assembly of claim 1,wherein the routing line is disposed vertically beyond the chip in thesecond direction.
 9. The assembly of claim 1, wherein the routing lineextends vertically beyond the bumped terminal and the filler in thefirst direction.
 10. The assembly of claim 1, wherein the routing lineextends laterally beyond the bumped terminal and the filler towards thechip.
 11. The assembly of claim 1, wherein the routing line extendswithin the cavity.
 12. The assembly of claim 1, wherein the routing linedoes not extend within the cavity.
 13. The assembly of claim 1, whereinthe routing line covers the filler in the first direction.
 14. Theassembly of claim 1, wherein the routing line does not cover the fillerin the first direction.
 15. The assembly of claim 1, wherein the routingline contacts the filler within the cavity.
 16. The assembly of claim 1,wherein the routing line contacts the filler outside the cavity.
 17. Theassembly of claim 1, wherein the routing line includes a distal end thatcontacts the filler within the cavity and is spaced from the bumpedterminal.
 18. The assembly of claim 1, wherein the routing line includesa distal end that contacts the filler outside the cavity and is spacedfrom the bumped terminal.
 19. The assembly of claim 1, wherein therouting line is essentially flat and parallel to the first and secondsurfaces of the chip.
 20. The assembly of claim 1, wherein the routingline includes a bent corner that slants vertically in the firstdirection as the bent corner extends laterally into the periphery of thecavity.
 21. The assembly of claim 1, wherein the routing line includes abent corner that slants vertically in the second direction as the bentcorner extends laterally into the periphery of the cavity.
 22. Theassembly of claim 1, wherein the bumped terminal has a curved shape inthe first and second directions.
 23. The assembly of claim 1, whereinthe bumped terminal is disposed within a periphery of the chip.
 24. Theassembly of claim 1, wherein the bumped terminal is disposed outside aperiphery of the chip.
 25. The assembly of claim 1, wherein the cavityextends across a majority of a diameter of the bumped terminal.
 26. Theassembly of claim 1, wherein the cavity extends across a majority of aheight of the filler.
 27. The assembly of claim 1, wherein the cavityextends across a majority of a diameter of the filler.
 28. The assemblyof claim 1, wherein the cavity extends across a majority of a diameterof the bumped terminal and a height and diameter of the filler.
 29. Theassembly of claim 1, wherein the cavity has a diameter that decreases asthe cavity extends in the second direction.
 30. The assembly of claim 1,wherein the cavity includes first and second opposing ends and curvedtapered sidewalls, the first and second ends of the cavity are adjacentto the bumped terminal, the first end of the cavity faces in the firstdirection, the second end of the cavity faces in the second directionand is disposed within a surface area of the first end of the cavity andwithin a surface area of the filler, and the curved tapered sidewallsare adjacent to the first and second ends of the cavity and slantinwardly towards the second end of the cavity.
 31. The assembly of claim30, wherein the surface area of the first end of the cavity is at least20 percent larger than a surface area of the second end of the cavity,and a surface area of the filler is at least 20 percent larger than thesurface area of the second end of the cavity.
 32. The assembly of claim1, wherein the filler fills the cavity.
 33. The assembly of claim 1,wherein the filler does not fill the cavity.
 34. The assembly of claim1, wherein the filler is disposed within the cavity.
 35. The assembly ofclaim 1, wherein the filler the extends outside the cavity.
 36. Theassembly of claim 1, wherein the filler fills a majority of the cavity,and a majority of the filler is disposed within the cavity.
 37. Theassembly of claim 1, wherein the filler fills essentially all of thecavity, and essentially all of the filler is disposed within the cavity.38. The assembly of claim 1, wherein the filler is electroplated metal.39. The assembly of claim 1, wherein the filler is solder.
 40. Theassembly of claim 1, wherein the filler is conductive adhesive.
 41. Theassembly of claim 1, wherein the connection joint is electroplatedmetal.
 42. The assembly of claim 1, wherein the connection joint iselectrolessly plated metal.
 43. The assembly of claim 1, wherein theconnection joint is solder.
 44. The assembly of claim 1, wherein theconnection joint is a stud bump.
 45. The assembly of claim 1, whereinthe connection joint is a wire bond.
 46. The assembly of claim 1,wherein the encapsulant contacts the chip and covers the chip in thefirst direction.
 47. The assembly of claim 1, wherein the encapsulantcontacts the filler and covers the filler in the first direction. 48.The assembly of claim 1, wherein the encapsulant contacts the routingline and the filler within the periphery of the cavity.
 49. The assemblyof claim 1, wherein the encapsulant contacts the routing line and thefiller within the cavity.
 50. The assembly of claim 1, wherein thelateral surface is an exposed major surface of the assembly.
 51. Theassembly of claim 1, including an insulative base that is laterallyaligned with the bumped terminal, the cavity and the filler at thelateral surface.
 52. The assembly of claim 51, wherein the insulativebase contacts the routing line and the bumped terminal, is overlapped bythe chip and extends vertically beyond the chip, the routing line andthe encapsulant in the second direction.
 53. The assembly of claim 51,wherein the insulative base is spaced from the filler.
 54. The assemblyof claim 51, wherein the insulative base surrounds and is adjacent tothe bumped terminal at the lateral surface.
 55. The assembly of claim 1,including an insulative adhesive that contacts the chip and theencapsulant and extends vertically beyond the chip in the seconddirection.
 56. The assembly of claim 55, wherein the insulative adhesivecontacts the filler and covers the filler in the first direction. 57.The assembly of claim 55, wherein the insulative adhesive contacts therouting line and the filler within the periphery of the cavity.
 58. Theassembly of claim 55, wherein the insulative adhesive contacts therouting line and the filler within the cavity.
 59. The assembly of claim1, including a contact terminal that contacts and is electricallyconnected to the bumped terminal and the filler, is spaced from therouting line and the connection joint and extends vertically beyond thechip, the routing line, the bumped terminal, the filler, the connectionjoint and the encapsulant in the second direction.
 60. The assembly ofclaim 1, wherein the assembly is a first-level package.
 61. Asemiconductor chip assembly, comprising: a semiconductor chip thatincludes first and second opposing surfaces, wherein the first surfaceof the chip includes a conductive pad; a conductive trace that includesa routing line, a bumped terminal and a filler, wherein the bumpedterminal includes a cavity; a connection joint that electricallyconnects the routing line and the pad; and an encapsulant that includesfirst and second opposing surfaces, wherein the first surface ofencapsulant faces in a first direction, the second surface of theencapsulant faces in a second direction opposite the first direction,the chip is embedded in the encapsulant, the routing line contacts thebumped terminal, contacts the filler within a periphery of the cavity,extends laterally beyond the bumped terminal and the filler towards thechip, extends vertically beyond the bumped terminal and the filler inthe first direction where the routing line contacts the bumped terminaland the filler and extends vertically beyond the chip in the seconddirection, the bumped terminal extends vertically beyond the routingline in the second direction and does not extend vertically beyond therouting line in the first direction, the cavity extends through thebumped terminal in the first and second directions and has a diameterthat decreases as the cavity extends in the second direction, the fillercontacts the bumped terminal in the cavity and extends vertically beyondthe routing line in the second direction, the bumped terminal, thecavity and the filler are disposed outside a periphery of the chip, arelaterally aligned with one another at a lateral surface that faces inthe second direction and are not covered in the second direction by theencapsulant or any other insulative material of the assembly, the bumpedterminal surrounds the filler and only the filler at the lateralsurface, is adjacent to the filler at the lateral surface and has asmaller surface area than the filler at the lateral surface, and theassembly is devoid of a printed circuit board.
 62. The assembly of claim61, wherein the chip is the only chip embedded in the encapsulant. 63.The assembly of claim 61, wherein the chip extends vertically beyond theconductive trace in the first direction.
 64. The assembly of claim 61,wherein the routing line contacts the filler in the cavity.
 65. Theassembly of claim 61, wherein the routing line contacts the filleroutside the cavity.
 66. The assembly of claim 61, wherein the routingline includes a distal end that contacts the filler within the cavityand is spaced from the bumped terminal.
 67. The assembly of claim 61,wherein the routing line includes a distal end that contacts the filleroutside the cavity and is spaced from the bumped terminal.
 68. Theassembly of claim 61, wherein the bumped terminal has curved taperedsidewalls that slant inwardly as the bumped terminal extends in thesecond direction.
 69. The assembly of claim 61, wherein the bumpedterminal forms a ring at the lateral surface.
 70. The assembly of claim61, wherein: the cavity extends across a majority of a diameter of thebumped terminal and a height and diameter of the filler; the cavityincludes first and second opposing ends and curved tapered sidewalls,the first and second ends of the cavity are adjacent to the bumpedterminal, the first end of the cavity faces in the first direction, thesecond end of the cavity faces in the second direction and is disposedwithin a surface area of the first end of the cavity and within asurface area of the filler, and the curved tapered sidewalls areadjacent to the first and second ends of the cavity and slant inwardlytowards the second end of the cavity; and the filler includes first andsecond opposing surfaces, the first surface of the filler faces in thefirst direction, and the second surface of the filler faces in thesecond direction and has identical size, shape and location as thesecond end of the cavity.
 71. The assembly of claim 70, wherein thesurface area of the first end of the cavity is at least 20 percentlarger than a surface area of the second end of the cavity, and thesurface area of the filler is at least 20 percent larger than thesurface area of the second end of the cavity.
 72. The assembly of claim61, wherein the filler fills the cavity.
 73. The assembly of claim 61,wherein the filler fills a majority of the cavity, and a majority of thefiller is disposed within the cavity.
 74. The assembly of claim 61,wherein the routing line is electroplated metal, the bumped terminal iselectroplated metal and the filler is electroplated metal, solder orconductive adhesive.
 75. The assembly of claim 61, wherein theencapsulant contacts the chip, the routing line and the filler andcovers the chip, the routing line and the filler in the first direction.76. The assembly of claim 61, wherein the encapsulant contacts therouting line and the filler within the periphery of the cavity.
 77. Theassembly of claim 61, wherein the encapsulant contacts the routing lineand the filler within the cavity.
 78. The assembly of claim 61, whereinthe lateral surface is an exposed major surface of the assembly.
 79. Theassembly of claim 61, including an insulative base that contacts therouting line and the bumped terminal, is overlapped by the chip, isspaced from the filler, extends vertically beyond the chip, the routingline and the encapsulant in the second direction and is laterallyaligned with the bumped terminal, the cavity and the filler at thelateral surface.
 80. The assembly of claim 61, wherein the assembly is afirst-level package.
 81. A semiconductor chip assembly, comprising: asemiconductor chip that includes first and second opposing surfaces,wherein the first surface of the chip includes a conductive pad; aconductive trace that includes a routing line, a bumped terminal and afiller, wherein the bumped terminal includes a cavity; a connectionjoint that electrically connects the routing line and the pad; aninsulative base; and an encapsulant that includes first and secondopposing surfaces, wherein the first surface of encapsulant faces in afirst direction, the second surface of the encapsulant faces in a seconddirection opposite the first direction, the chip is embedded in theencapsulant, the routing line contacts the bumped terminal, contacts thefiller within a periphery of the cavity, extends laterally beyond thebumped terminal and the filler towards the chip, extends verticallybeyond the bumped terminal and the filler in the first direction wherethe routing line contacts the bumped terminal and the filler and extendsvertically beyond the chip in the second direction, the bumped terminalextends vertically beyond the routing line in the second direction anddoes not extend vertically beyond the routing line in the firstdirection, the cavity extends through the bumped terminal in the firstand second directions, the insulative base contacts the routing line andthe bumped terminal, is overlapped by the chip, is spaced from thefiller and extends vertically beyond the chip, the routing line and theencapsulant in the second direction, the filler contacts the bumpedterminal in the cavity and extends vertically beyond the routing line inthe second direction, the bumped terminal, the cavity and the filler aredisposed outside a periphery of the chip and are not covered in thesecond direction by the encapsulant, the insulative base or any otherinsulative material of the assembly, the bumped terminal, the cavity,the filler and the insulative base are laterally aligned with oneanother at a lateral surface that faces in the second direction, thebumped terminal surrounds the filler and only the filler at the lateralsurface, is adjacent to the filler at the lateral surface and has asmaller surface area than the filler at the lateral surface, theinsulative base surrounds and is adjacent to the bumped terminal at thelateral surface, and the assembly is devoid of a printed circuit board.82. The assembly of claim 81, wherein the chip is the only chip embeddedin the encapsulant.
 83. The assembly of claim 81, wherein the chipextends vertically beyond the conductive trace in the first direction.84. The assembly of claim 81, wherein the routing line contacts thefiller in the cavity.
 85. The assembly of claim 81, wherein the routingline contacts the filler outside the cavity.
 86. The assembly of claim81, wherein the routing line includes a distal end that contacts thefiller within the cavity and is spaced from the bumped terminal.
 87. Theassembly of claim 81, wherein the routing line includes a distal endthat contacts the filler outside the cavity and is spaced from thebumped terminal.
 88. The assembly of claim 81, wherein the bumpedterminal has curved tapered sidewalls that slant inwardly as the bumpedterminal extends in the second direction.
 89. The assembly of claim 81,wherein the bumped terminal forms a ring at the lateral surface.
 90. Theassembly of claim 81, wherein: the cavity extends across a majority of adiameter of the bumped terminal and a height and diameter of the filler;the cavity includes first and second opposing ends and curved taperedsidewalls, the first and second ends of the cavity are adjacent to thebumped terminal, the first end of the cavity faces in the firstdirection, the second end of the cavity faces in the second directionand is disposed within a surface area of the first end of the cavity andwithin a surface area of the filler, and the curved tapered sidewallsare adjacent to the first and second ends of the cavity and slantinwardly towards the second end of the cavity; and the filler includesfirst and second opposing surfaces, the first surface of the fillerfaces in the first direction, and the second surface of the filler facesin the second direction and has identical size, shape and location asthe second end of the cavity.
 91. The assembly of claim 90, wherein thesurface area of the first end of the cavity is at least 20 percentlarger than a surface area of the second end of the cavity, and thesurface area of the filler is at least 20 percent larger than thesurface area of the second end of the cavity.
 92. The assembly of claim81, wherein the filler fills the cavity.
 93. The assembly of claim 81,wherein the filler fills a majority of the cavity, and a majority of thefiller is disposed within the cavity.
 94. The assembly of claim 81,wherein the routing line is electroplated metal, the bumped terminal iselectroplated metal and the filler is electroplated metal, solder orconductive adhesive.
 95. The assembly of claim 81, wherein theencapsulant contacts the chip, the routing line and the filler andcovers the chip, the routing line and the filler in the first direction.96. The assembly of claim 81, wherein the encapsulant contacts therouting line and the filler within the periphery of the cavity.
 97. Theassembly of claim 81, wherein the encapsulant contacts the routing lineand the filler within the cavity.
 98. The assembly of claim 81, whereinthe encapsulant contacts the insulative base and covers the insulativebase in the first direction.
 99. The assembly of claim 81, wherein thelateral surface is an exposed major surface of the assembly.
 100. Theassembly of claim 81, wherein the assembly is a first-level package.